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Wikipedia

PHP

January 13, 2023

This article is about the scripting language. For other uses, see PHP (disambiguation).

PHP is a general-purpose scripting language geared toward web development.[7] It was originally created by Danish-Canadian programmer Rasmus Lerdorf in 1993 and released in 1995.[8][9] The PHP reference implementation is now produced by The PHP Group.[10] PHP was originally an abbreviation of Personal Home Page,[11][12] but it now stands for the recursive initialism PHP: Hypertext Preprocessor.[13]

PHP
ParadigmMulti-paradigm: imperative, functional, object-oriented, procedural, reflective
Designed byRasmus Lerdorf
DeveloperThe PHP Development Team, Zend Technologies, PHP Foundation
First appearedJune 8, 1995; 27 years ago (1995-06-08)[1][2]
Stable release
8.2.1 / 2023-01-05[3]
Typing disciplineDynamic, weak, gradual[4]
Implementation languageC (primarily; some components C++)
OSUnix-like, Windows, macOS, IBM i, OpenVMS
Licensedual licensed GNU General Public License version 2 or any later version and PHP License for PHP versions 3.0 or earlier.[5] Only PHP License (most of Zend engine under Zend Engine License) for 3.01x and later versions.
Filename extensions.php,.phar,.phtml,.pht,.phps
Websitewww.php.net
Major implementations
Zend Engine, HHVM, PeachPie, Quercus, Parrot
Influenced by
Perl, HTML, C, C++, Java,[citation needed] Tcl,[2] JavaScript, Hack[6]
Influenced
Hack, JSP, ASP
  • PHP Programming at Wikibooks

PHP code is usually processed on a web server by a PHP interpreter implemented as a module, a daemon or as a Common Gateway Interface (CGI) executable. On a web server, the result of the interpreted and executed PHP code – which may be any type of data, such as generated HTML or binary image data – would form the whole or part of an HTTP response. Various web template systems, web content management systems, and web frameworks exist which can be employed to orchestrate or facilitate the generation of that response. Additionally, PHP can be used for many programming tasks outside the web context, such as standalone graphical applications[14] and robotic drone control.[15] PHP code can also be directly executed from the command line.

The standard PHP interpreter, powered by the Zend Engine, is free software released under the PHP License. PHP has been widely ported and can be deployed on most web servers on a variety of operating systems and platforms.[16]

The PHP language evolved without a written formal specification or standard until 2014, with the original implementation acting as the de facto standard which other implementations aimed to follow. Since 2014, work has gone on to create a formal PHP specification.[17]

W3Techs reports that, as of October 2022, "PHP is used by 74.4% of all the websites whose server-side programming language we know."[18] PHP version 7.4 is the most used version. Support for version 7.3 was dropped on 6 December 2021.

History

 
 
 
Rasmus Lerdorf, creator of PHP; and Andi Gutmans and Zeev Suraski, creators of the Zend Engine

Early history

PHP development began in 1993[8] when Rasmus Lerdorf wrote several Common Gateway Interface (CGI) programs in C,[19][20] which he used to maintain his personal homepage. He extended them to work with web forms and to communicate with databases, and called this implementation "Personal Home Page/Forms Interpreter" or PHP/FI.

PHP/FI could be used to build simple, dynamic web applications. To accelerate bug reporting and improve the code, Lerdorf initially announced the release of PHP/FI as "Personal Home Page Tools (PHP Tools) version 1.0" on the Usenet discussion group comp.infosystems.www.authoring.cgi on June 8, 1995.[1][21] This release already had the basic functionality that PHP has today. This included Perl-like variables, form handling, and the ability to embed HTML. The syntax resembled that of Perl, but was simpler, more limited and less consistent.[10]

An example of the early PHP syntax:[22]

<!--include /text/header.html--> <!--getenv HTTP_USER_AGENT--> <!--if substr $exec_result Mozilla--> Hey, you are using Netscape!<p> <!--endif--> <!--sql database select * from table where user='$username'--> <!--ifless $numentries 1--> Sorry, that record does not exist<p> <!--endif exit--> Welcome <!--$user-->!<p> You have <!--$index:0--> credits left in your account.<p> <!--include /text/footer.html-->

Early PHP was not intended to be a new programming language, and grew organically, with Lerdorf noting in retrospect: "I don't know how to stop it, there was never any intent to write a programming language [...] I have absolutely no idea how to write a programming language, I just kept adding the next logical step on the way."[23] A development team began to form and, after months of work and beta testing, officially released PHP/FI 2 in November 1997.

The fact that PHP was not originally designed, but instead was developed organically has led to inconsistent naming of functions and inconsistent ordering of their parameters.[24] In some cases, the function names were chosen to match the lower-level libraries which PHP was "wrapping",[25] while in some very early versions of PHP the length of the function names was used internally as a hash function, so names were chosen to improve the distribution of hash values.[26]

PHP 3 and 4

 
This is an example of PHP code for the WordPress content management system.

Zeev Suraski and Andi Gutmans rewrote the parser in 1997 and formed the base of PHP 3, changing the language's name to the recursive acronym PHP: Hypertext Preprocessor.[10][27] Afterwards, public testing of PHP 3 began, and the official launch came in June 1998. Suraski and Gutmans then started a new rewrite of PHP's core, producing the Zend Engine in 1999.[28] They also founded Zend Technologies in Ramat Gan, Israel.[10]

On 22 May 2000, PHP 4, powered by the Zend Engine 1.0, was released.[10] By August 2008, this branch had reached version 4.4.9. PHP 4 is now no longer under development and nor are any security updates planned to be released.[29][30]

PHP 5

On 1 July 2004, PHP 5 was released, powered by the new Zend Engine II.[10] PHP 5 included new features such as improved support for object-oriented programming, the PHP Data Objects (PDO) extension (which defines a lightweight and consistent interface for accessing databases), and numerous performance enhancements.[31] In 2008, PHP 5 became the only stable version under development. Late static binding had been missing from previous versions of PHP, and was added in version 5.3.[32][33]

Many high-profile open-source projects ceased to support PHP 4 in new code from February 5, 2008, because of the GoPHP5 initiative,[34] provided by a consortium of PHP developers promoting the transition from PHP 4 to PHP 5.[35][36]

Over time, PHP interpreters became available on most existing 32-bit and 64-bit operating systems, either by building them from the PHP source code, or by using pre-built binaries.[37] For PHP versions 5.3 and 5.4, the only available Microsoft Windows binary distributions were 32-bit IA-32 builds,[38][39] requiring Windows 32-bit compatibility mode while using Internet Information Services (IIS) on a 64-bit Windows platform. PHP version 5.5 made the 64-bit x86-64 builds available for Microsoft Windows.[40]

Official security support for PHP 5.6 ended on 31 December 2018.[41]

PHP 6 and Unicode

PHP received mixed reviews due to lacking native Unicode support at the core language level.[42][43] In 2005, a project headed by Andrei Zmievski was initiated to bring native Unicode support throughout PHP, by embedding the International Components for Unicode (ICU) library, and representing text strings as UTF-16 internally.[44] Since this would cause major changes both to the internals of the language and to user code, it was planned to release this as version 6.0 of the language, along with other major features then in development.[45]

However, a shortage of developers who understood the necessary changes, and performance problems arising from conversion to and from UTF-16, which is rarely used in a web context, led to delays in the project.[46] As a result, a PHP 5.3 release was created in 2009, with many non-Unicode features back-ported from PHP 6, notably namespaces. In March 2010, the project in its current form was officially abandoned, and a PHP 5.4 release was prepared containing most remaining non-Unicode features from PHP 6, such as traits and closure re-binding.[47] Initial hopes were that a new plan would be formed for Unicode integration, but by 2014 none had been adopted.

PHP 7

During 2014 and 2015, a new major PHP version was developed, PHP 7. The numbering of this version involved some debate among internal developers.[48] While the PHP 6 Unicode experiment had never been released, several articles and book titles referenced the PHP 6 name, which might have caused confusion if a new release were to reuse the name.[49] After a vote, the name PHP 7 was chosen.[50]

The foundation of PHP 7 is a PHP branch that was originally dubbed PHP next generation (phpng). It was authored by Dmitry Stogov, Xinchen Hui and Nikita Popov,[51] and aimed to optimize PHP performance by refactoring the Zend Engine while retaining near-complete language compatibility.[52] By 14 July 2014, WordPress-based benchmarks, which served as the main benchmark suite for the phpng project, showed an almost 100% increase in performance. Changes from phpng make it easier to improve performance in future versions, as more compact data structures and other changes are seen as better suited for a successful migration to a just-in-time (JIT) compiler.[53] Because of the significant changes, the reworked Zend Engine was called Zend Engine 3, succeeding Zend Engine 2 used in PHP 5.[54]

Because of the major internal changes in phpng, it must receive a new major version number of PHP, rather than a minor PHP 5 release, according to PHP's release process.[55] Major versions of PHP are allowed to break backward-compatibility of code and therefore PHP 7 presented an opportunity for other improvements beyond phpng that require backward-compatibility breaks. In particular, it involved the following changes:

  • Many fatal or recoverable-level legacy PHP error mechanisms were replaced with modern object-oriented exceptions.[56]
  • The syntax for variable dereferencing was reworked to be internally more consistent and complete, allowing the use of the operators ->, [], (),{}, and ::, with arbitrary meaningful left-side expressions.[57]
  • Support for legacy PHP 4-style constructor methods was deprecated.[58]
  • The behavior of the foreach statement was changed to be more predictable.[59]
  • Constructors for the few classes built-in to PHP which returned null upon failure were changed to throw an exception instead, for consistency.[60]
  • Several unmaintained or deprecated server application programming interfaces (SAPIs) and extensions were removed from the PHP core, most notably the legacy mysql extension.[61]
  • The behavior of the list() operator was changed to remove support for strings.[62]
  • Support was removed for legacy ASP-style delimiters <% and %> and <script language="php"> ... </script>.[63]
  • An oversight allowing a switch statement to have multiple default clauses was fixed.[64]
  • Support for hexadecimal number support in some implicit conversions from strings to number types was removed.[65]
  • The left-shift and right-shift operators were changed to behave more consistently across platforms.[66]
  • Conversions between floating-point numbers and integers were changed (e.g. infinity changed to convert to zero) and implemented more consistently across platforms.[66][67]

PHP 7 also included new language features. Most notably, it introduced return type declarations for functions[68] which complement the existing parameter type declarations, and support for the scalar types (integer, float, string, and boolean) in parameter and return type declarations.[69]

PHP 8

PHP 8 was released on November 26, 2020. PHP 8 is a major version and has breaking changes from previous versions.[70][71] New features and notable changes include:

Just-in-time compilation

Just-in-time compilation is supported in PHP 8.[72]

PHP 8's JIT compiler can provide substantial performance improvements for some use cases,[73][74] while PHP developer Nikita Popov stated that the performance improvements for most websites will be less substantial than the upgrade from PHP 5 to PHP 7.[75] Substantial improvements are expected more for mathematical-type operations than for common web-development use cases.[75] Additionally, the JIT compiler provides future potential to move some code from C to PHP, due to the performance improvements for some use cases.[76]

Addition of the match expression

Main article: PHP syntax and semantics § Match_expression

PHP 8 introduced the match expression.[77] The match expression is conceptually similar to a switch statement and is more compact for some use cases.[78] Because match is an expression, its result can be caught into a variable or returned from a function.[79]

Type changes and additions

PHP 8 introduced union types, a new static return type, and a new mixed type.[70]

"Attributes", often referred to as "annotations" in other programming languages, were added in PHP 8, which allow metadata to be added to classes.[70]

throw was changed from being a statement to being an expression.[80] This allows exceptions to be thrown in places that were not previously possible.[70]

Syntax changes and additions

PHP 8 includes changes to allow alternate, more concise, or more consistent syntaxes in a number of scenarios. For example, the nullsafe operator is similar to the null coalescing operator ??, but used when calling methods.[81] The following code snippet will not throw an error if getBirthday() returns null: 

$human_readable_date = $user->getBirthday()?->diffForHumans();

Constructor property promotion has been added as "syntactic sugar," allowing class properties to be set automatically when parameters are passed into a class constructor.[70] This reduces the amount of boilerplate code that must be written.

Other minor changes include support for use of ::class on objects, which serves as an alternative for the use of get_class();[70] non-capturing catches in try-catch blocks; variable syntax tweaks to resolve inconsistencies; support for named arguments; and support for trailing commas in parameter lists, which adds consistency with support for trailing commas in other contexts, such as in arrays.

Standard library changes and additions

  • Weak maps were added in PHP 8. A WeakMap holds references to objects, but these references do not prevent such objects from being garbage collected.[82] This can provide performance improvements in scenarios where data is being cached; this is of particular relevance for object relational mappings (ORM).[70]
  • Various adjustments to interfaces, such as adding support for creating DateTime objects from interfaces, and the addition of a Stringable interface that can be used for type hinting.
  • Various new functions including str_contains(), str_starts_with(), and str_ends_with();[83] fdiv(); get_debug_type(); and get_resource_id()
  • Object implementation of token_get_all()

Additional changes

  • Type annotations were also added into PHP's C source code itself to allow internal functions and methods to have "complete type information in reflection."[84]
  • Inheritance with private methods
  • Abstract methods in traits improvements

PHP 8.1

PHP 8.1 was released on December 8, 2021 and included a number of new features and improvements over previous versions. Here is a more detailed look at some of the key features and improvements in PHP 8.1:

  • Union types: This feature allows you to specify that a variable can have multiple types, such as an integer or a string. This can be useful for writing more flexible and robust code, as it allows you to handle a wider range of input values.
  • Nullsafe operator: This operator allows you to chain method calls without worrying about null references. For example, if you want to call a method on an object that may be null, you can use the nullsafe operator to ensure that the method is only called if the object is not null.
  • Match expression: This is a more concise and flexible way to perform matching on values. It allows you to specify multiple cases and their associated values, and then use the match keyword to select the appropriate case based on the value of an expression.
  • Improved performance: PHP 8.1 includes various performance improvements, such as faster array operations and better memory usage. These improvements can help make your code run faster and more efficiently.
  • New error handling features: PHP 8.1 introduces a new throws keyword that allows you to specify which exceptions a function can throw, and a new assert() function that can be used to check for certain conditions at runtime. These features can help you write more reliable and robust code.
  • Other new features: PHP 8.1 also includes other new features such as support for named arguments, support for attributes (similar to annotations in other languages), and improved support for Unicode.[85]

The match expression is a new feature in PHP 8.1 that allows you to perform value matching in a more concise and flexible way. It is similar to a switch statement, but with some additional features and syntax improvements.

Here is an example of how you can use the match expression in PHP:

$value = 3; $result = match ($value) { 0 => 'The value is zero', 1, 2, 3 => 'The value is one, two, or three', default => 'The value is something else', }; echo $result; // Outputs: "The value is one, two, or three"

In this example, the match expression compares the value of $value to the different cases specified in the curly braces. If $value matches one of the cases, the corresponding value is returned. If none of the cases match, the default case is used.

One of the main benefits of the match expression is that it allows you to specify multiple values for a single case, as shown in the example above. This can help make your code more concise and easier to read.

The match expression also allows you to specify a when clause for each case, which can be used to specify additional conditions that must be met for the case to be matched. For example:

$value = 3; $result = match ($value) { 0 => 'The value is zero', 1, 2, 3 when $value > 1 => 'The value is two or three', default => 'The value is something else', }; echo $result; // Outputs: "The value is two or three"

Overall, the match expression is a useful addition to PHP that can make it easier to write code that performs value matching and conditional processing.

Assert() Error handling

The assert() function and the throws keyword are new error-handling features in PHP 8.1 that can help you write more reliable and robust code.

The assert() function is used to check for certain conditions at runtime. If the condition is not met, the function generates an AssertionError exception. For example:

assert($x > 0, '$x must be greater than zero');

In this example, the assert() function checks whether $x is greater than zero. If it is not, an AssertionError exception is thrown with the message "$x must be greater than zero". The throws keyword, on the other hand, is used to specify which exceptions a function or method can throw. This can be helpful for documenting your code and making it easier for other developers to understand how your functions and methods behave. For example:

function divide(int $a, int $b): int { if ($b === 0) { throw new DivisionByZeroError('Cannot divide by zero'); } return $a / $b; }

In this example, the divide() function uses the throws keyword to specify that it can throw a DivisionByZeroError exception if the second argument is zero.

Overall, the assert() function and the throws keyword are useful tools for handling errors and exceptions in PHP, and can help you write more reliable and robust code.[86]

Support for enumerations

Support for enumerations was one of the most prominent features of PHP 8.1.[87] Enums allow developers to programmatically enforce states in their codebase. Below is an example of an enum: 

<?php namespace App\Enums; enum InvoiceStatus: string { case draft = 'draft'; case pending = 'pending'; case paid = 'paid'; case expired = 'expired'; }

Other PHP 8.1 features

  • Support for `read-only` properties was added.
  • After the introduction of array unpacking in PHP 7.4 with consecutive numbered keys, PHP 8.1 introduced support for array unpacking with string keys.
  • PHP 8.1 added support for using `new` in initializers.
  • A new syntax was added for creating callables.
  • PHP 8.1 brought support for Pure Intersection Types, after in the introduction of union types in PHP 8.0.

PHP 8.2

PHP 8.2 includes a number of new features and improvements. Here are some of the main ones:

  1. Union Types: Union types allow you to specify that a function or method parameter can accept multiple types, separated by the "|" symbol. This can help to improve type safety and reduce the need for type juggling.
  2. Nullsafe Operator: The nullsafe operator (?->) allows you to chain method calls without having to check for null values at each step. This can help to reduce the need for null checks and make your code more concise.
  3. Match Expression: The match expression allows you to perform pattern matching on values, similar to a switch statement in other languages. This can be a more concise and expressive way to handle multiple conditions.
  4. Improved Type Variance: PHP 8.2 introduces improved type variance for generic types, allowing you to specify whether a generic type is covariant, contravariant, or invariant. This can help to improve type safety and flexibility when working with generic types.
  5. Performance Improvements: PHP 8.2 includes various performance improvements, including faster JIT compilation, faster garbage collection, and improved handling of large arrays. These improvements can help to make PHP applications faster and more efficient.
  6. Deprecations: Some features have been deprecated in PHP 8.2, including the assert() function when used with a string argument, and the list() construct with a single array element. It's important to be aware of these deprecations if you are upgrading from an earlier version of PHP.

Here are some examples of features that have been deprecated in PHP 8.2:

  1. assert() function with string argument: The assert() function can be used to perform runtime checks, but it has been deprecated when used with a string argument. Instead, you should use the assert() function with a boolean argument or an expression.
  2. list() construct with a single array element: The list() construct allows you to unpack the elements of an array into separate variables. It has been deprecated when used with a single array element, as this usage was considered confusing and error-prone.
  3. create_function(): The create_function() function has been deprecated, as it has been superseded by anonymous functions, which are more flexible and easier to use.
  4. mb_ereg_replace_callback(): The mb_ereg_replace_callback() function has been deprecated, as it has been superseded by the preg_replace_callback() function, which provides similar functionality and is more widely used.

New "Random" extension

The "Random" extension provides a new object-oriented API for generating random values in PHP. It includes several classes ("Engine"s) that implement different algorithms for generating random numbers and storing their state within objects. This allows for multiple independent seedable sequences, which can be useful in certain contexts, such as testing or simulation.

The \Random\Randomizer class provides a high-level interface for using the engine's randomness to generate a random integer, shuffle an array or string, select random array keys, and more. This can be a convenient way to perform these common tasks without having to directly use the lower-level engine classes.

It's worth noting that the "Random" extension is not enabled by default in PHP, and you will need to install and enable it in your PHP environment in order to use its features. You can find more information about the extension in the official PHP documentation.[88]

Release history

Version Release date Supported until[89] Notes
Old version, no longer maintained: 1.0 8 June 1995 Officially called "Personal Home Page Tools (PHP Tools)". This is the first use of the name "PHP".[10]
Old version, no longer maintained: 2.0 1 November 1997 Officially called "PHP/FI 2.0". This is the first release that could actually be characterised as PHP, being a standalone language with many features that have endured to the present day.
Old version, no longer maintained: 3.0 6 June 1998 20 October 2000[89] Development moves from one person to multiple developers. Zeev Suraski and Andi Gutmans rewrite the base for this version.[10]
Old version, no longer maintained: 4.0 22 May 2000[90] 23 June 2001[89] Added more advanced two-stage parse/execute tag-parsing system called the Zend engine.[91]
Old version, no longer maintained: 4.1 10 December 2001[92] 12 March 2002[89] Introduced "superglobals" ($_GET, $_POST, $_SESSION, etc.)[91]
Old version, no longer maintained: 4.2 22 April 2002[93] 6 September 2002[89] Disabled register_globals by default. Data received over the network is not inserted directly into the global namespace anymore, closing possible security holes in applications.[91]
Old version, no longer maintained: 4.3 27 December 2002[94] 31 March 2005[89] Introduced the command-line interface (CLI), to supplement the CGI.[91][95]
Old version, no longer maintained: 4.4 11 July 2005[96] 7 August 2008[89] Fixed a memory corruption bug, which required breaking binary compatibility with extensions compiled against PHP version 4.3.x.[97]
Old version, no longer maintained: 5.0 13 July 2004[98] 5 September 2005[89] Zend Engine II with a new object model.[99]
Old version, no longer maintained: 5.1 24 November 2005[100] 24 August 2006[89] Performance improvements with introduction of compiler variables in re-engineered PHP Engine.[99] Added PHP Data Objects (PDO) as a consistent interface for accessing databases.[101]
Old version, no longer maintained: 5.2 2 November 2006[102] 6 January 2011[89] Enabled the filter extension by default. Native JSON support.[99]
Old version, no longer maintained: 5.3 30 June 2009[103] 14 August 2014[89] Namespace support; late static bindings, jump label (limited goto), anonymous functions, closures, PHP archives (phar), garbage collection for circular references, improved Windows support, sqlite3, mysqlnd as a replacement for libmysql as underlying library for the extensions that work with MySQL, fileinfo as a replacement for mime_magic for better MIME support, the Internationalization extension, and deprecation of ereg extension.
Old version, no longer maintained: 5.4 1 March 2012[104] 3 September 2015[89] Trait support, short array syntax support. Removed items: register_globals, safe_mode, allow_call_time_pass_reference, session_register(), session_unregister() and session_is_registered(). Built-in web server.[105] Several improvements to existing features, performance and reduced memory requirements.
Old version, no longer maintained: 5.5 20 June 2013[106] 10 July 2016[107] Support for generators, finally blocks for exceptions handling, OpCache (based on Zend Optimizer+) bundled in official distribution.[108]
Old version, no longer maintained: 5.6 28 August 2014[109] 31 December 2018[107] Constant scalar expressions, variadic functions, argument unpacking, new exponentiation operator, extensions of the use statement for functions and constants, new phpdbg debugger as a SAPI module, and other smaller improvements.[110]
6.x Not released — Abandoned version of PHP that planned to include native Unicode support.[111][112]
Old version, no longer maintained: 7.0 3 December 2015[113] 10 January 2019[55] Zend Engine 3 (performance improvements[53] and 64-bit integer support on Windows[114]), uniform variable syntax,[57] AST-based compilation process,[115] added Closure::call(),[116] bitwise shift consistency across platforms,[117] ?? (null coalesce) operator,[118] Unicode code point escape syntax,[119] return type declarations,[68] scalar type (integer, float, string and boolean) declarations,[69] <=> "spaceship" three-way comparison operator,[120] generator delegation,[121] anonymous classes,[122] simpler and more consistently available CSPRNG API,[123] replacement of many remaining internal PHP "errors" with the more modern exceptions,[56] and shorthand syntax for importing multiple items from a namespace.[124]
Old version, no longer maintained: 7.1 1 December 2016 1 December 2019[107] void return type,[125] class constant visibility modifiers[126]
Old version, no longer maintained: 7.2 30 November 2017 30 November 2020[107] Object parameter and return type declaration,[127] Libsodium extension,[128] abstract method overriding,[129] parameter type widening[130]
Old version, no longer maintained: 7.3 6 December 2018[131] 6 December 2021 Flexible Heredoc and Nowdoc syntax,[132] support for reference assignment and array deconstruction with list(),[133] PCRE2 support,[134] hrtime() function[135]
Old version, no longer maintained: 7.4 28 November 2019[136] 28 November 2022 Typed properties 2.0,[137] preloading,[138] null-coalescing assignment operator,[139] improve openssl_random_pseudo_bytes,[140] Weak References,[82] FFI – foreign function interface,[141] always available hash extension,[142] password hash registry,[143] multibyte string splitting,[144] reflection for references,[145] unbundle ext/wddx,[146] new custom object serialization mechanism[147]
Older version, yet still maintained: 8.0 26 November 2020[148] 26 November 2023 Just-In-Time (JIT) compilation,[72] arrays starting with a negative index,[149] stricter/saner language semantics (validation for abstract trait methods),[150] saner string to number comparisons,[151] saner numeric strings,[152] TypeError on invalid arithmetic/bitwise operators,[153] reclassification of various engine errors,[154] consistent type errors for internal functions,[155] fatal error for incompatible method signatures[156]), locale-independent float to string conversion,[157] variable syntax tweaks,[158] attributes,[159][160][161][162] named arguments,[163] match expression,[164] constructor property promotion,[165] union types,[166] mixed type,[167] static return type,[168] nullsafe operator,[81] non-capturing catches,[169] throw expression,[80] JSON extension is always available.[170]
Older version, yet still maintained: 8.1 25 November 2021[171] 25 November 2024 Explicit octal integer literal notation,[172] enumerations,[173] readonly properties,[174] first-class callable syntax,[175] new in initializers,[176] pure intersection types,[177] never return type,[178] final class constraints,[179] fibers[180]
Current stable version: 8.2 8 December 2022[181] 8 December 2025 Readonly classes,[182] null, false, and true as stand-alone types,[183][184] locale-independent case conversion[185]
Future release: 8.3 23 November 2023[186] 23 November 2026
Legend:
Old version
Older version, still maintained
Latest version
Latest preview version
Future release

Beginning on 28 June 2011, the PHP Development Team implemented a timeline for the release of new versions of PHP.[55] Under this system, at least one release should occur every month. Once per year, a minor release should occur which may include new features. Every minor release should at least be supported for two years with security and bug fixes, followed by at least one year of only security fixes, for a total of a three-year release process for every minor release. No new features, unless small and self-contained, are to be introduced into a minor release during the three-year release process.

Mascot

 
The elePHPant, PHP mascot

The mascot of the PHP project is the elePHPant, a blue elephant with the PHP logo on its side, designed by Vincent Pontier[187] in 1998.[188] "The (PHP) letters were forming the shape of an elephant if viewed in a sideways angle."[189] The elePHPant is sometimes differently colored when in plush toy form.

Many variations of this mascot have been made over the years. Only the elePHPants based on the original design by Vincent Pontier are considered official by the community.[190] These are collectible and some of them are extremely rare.[191]

Syntax

Main article: PHP syntax and semantics
 
A "Hello World" application in PHP 7.4 running on its built-in development server

The following "Hello, World!" program is written in PHP code embedded in an HTML document: 

<!DOCTYPE html> <html> <head> <title>PHP "Hello, World!" program</title> </head> <body>  <?php  echo '<p>Hello, World!</p>';  ?>  </body> </html>

However, as no requirement exists for PHP code to be embedded in HTML, the simplest version of Hello, World! may be written like this, with the closing tag ?> omitted as preferred in files containing pure PHP code.[192]

<?php echo 'Hello, World!';

The PHP interpreter only executes PHP code within its delimiters. Anything outside of its delimiters is not processed by PHP, although non-PHP text is still subject to control structures described in PHP code. The most common delimiters are <?php to open and ?> to close PHP sections. The shortened form <? also exists. This short delimiter makes script files less portable, since support for them can be disabled in the local PHP configuration and it is therefore discouraged.[193][194] Conversely, there is no recommendation against the echo short tag <?=.[195] Prior to PHP 5.4.0, this short syntax for echo only works with the short_open_tag configuration setting enabled, while for PHP 5.4.0 and later it is always available.[196][197][193] The purpose of all these delimiters is to separate PHP code from non-PHP content, such as JavaScript code or HTML markup.[198] So the shortest "Hello, World!" program written in PHP is: 

<?='Hello, World!';

The first form of delimiters, <?php and ?>, in XHTML and other XML documents, creates correctly formed XML processing instructions.[199] This means that the resulting mixture of PHP code and other markup in the server-side file is itself well-formed XML.

Variables are prefixed with a dollar symbol, and a type does not need to be specified in advance. PHP 5 introduced type declarations that allows functions to force their parameters to be objects of a specific class, arrays, interfaces or callback functions. However, before PHP 7, type declarations could not be used with scalar types such as integer or string.[69]

Below is an example of how PHP variables are declared and initialized. 

<?php $name = 'John'; // variable of string type being declared and initialized $age = 18; // variable of integer type being declared and initialized $height = 5.3; // variable of double type being declared and initialized echo $name . ' is ' . $height . "m tall\n"; // concatenating variables and strings echo "$name is $age years old."; // interpolating variables to string ?>

Unlike function and class names, variable names are case sensitive. Both double-quoted ("") and heredoc strings provide the ability to interpolate a variable's value into the string.[200] PHP treats newlines as whitespace in the manner of a free-form language, and statements are terminated by a semicolon.[201] PHP has three types of comment syntax: /* */ marks block and inline comments; // or # are used for one-line comments.[202] The echo statement is one of several facilities PHP provides to output text.

In terms of keywords and language syntax, PHP is similar to the C style syntax. if conditions, for and while loops, and function returns are similar in syntax to languages such as C, C++, C#, Java and Perl.

Data types

PHP is loosely typed. It stores integers in a platform-dependent range, either as a 32, 64 or 128-bit signed integer equivalent to the C-language long type. Unsigned integers are converted to signed values in certain situations, which is different behavior to many other programming languages.[203] Integer variables can be assigned using decimal (positive and negative), octal, hexadecimal, and binary notations.

Floating point numbers are also stored in a platform-specific range. They can be specified using floating point notation, or two forms of scientific notation.[204] PHP has a native Boolean type that is similar to the native Boolean types in Java and C++. Using the Boolean type conversion rules, non-zero values are interpreted as true and zero as false, as in Perl and C++.[204]

The null data type represents a variable that has no value; NULL is the only allowed value for this data type.[204]

Variables of the "resource" type represent references to resources from external sources. These are typically created by functions from a particular extension, and can only be processed by functions from the same extension; examples include file, image, and database resources.[204]

Arrays can contain elements of any type that PHP can handle, including resources, objects, and even other arrays. Order is preserved in lists of values and in hashes with both keys and values, and the two can be intermingled.[204] PHP also supports strings, which can be used with single quotes, double quotes, nowdoc or heredoc syntax.[205]

The Standard PHP Library (SPL) attempts to solve standard problems and implements efficient data access interfaces and classes.[206]

Functions

PHP defines a large array of functions in the core language and many are also available in various extensions; these functions are well documented in the online PHP documentation.[207] However, the built-in library has a wide variety of naming conventions and associated inconsistencies, as described under history above.

Custom functions may be defined by the developer: 

function myAge(int $birthYear): string { // calculate the age by subtracting the birth year from the current year. $yearsOld = date('Y') - $birthYear; // return the age in a descriptive string. return $yearsOld . ($yearsOld == 1 ? ' year' : ' years'); } echo 'I am currently ' . myAge(1995) . ' old.';

As of 2023, the output of the above sample program is "I am currently 28 years old."

In lieu of function pointers, functions in PHP can be referenced by a string containing their name. In this manner, normal PHP functions can be used, for example, as callbacks or within function tables.[208] User-defined functions may be created at any time without being prototyped.[207][208] Functions may be defined inside code blocks, permitting a run-time decision as to whether or not a function should be defined. There is a function_exists function that determines whether a function with a given name has already been defined. Function calls must use parentheses, with the exception of zero-argument class constructor functions called with the PHP operator new, in which case parentheses are optional.

Since PHP 4.0.1 create_function(), a thin wrapper around eval(), allowed normal PHP functions to be created during program execution; it was deprecated in PHP 7.2 and removed in PHP 8.0[209] in favor of syntax for anonymous functions or "closures"[210] that can capture variables from the surrounding scope, which was added in PHP 5.3. Shorthand arrow syntax was added in PHP 7.4:[211]

function getAdder($x) { return fn($y) => $x + $y; } $adder = getAdder(8); echo $adder(2); // prints "10"

In the example above, getAdder() function creates a closure using passed argument $x (the keyword use imports a variable from the lexical context), which takes an additional argument $y, and returns the created closure to the caller. Such a function is a first-class object, meaning that it can be stored in a variable, passed as a parameter to other functions, etc.[212]

Unusually for a dynamically typed language, PHP supports type declarations on function parameters, which are enforced at runtime. This has been supported for classes and interfaces since PHP 5.0, for arrays since PHP 5.1, for "callables" since PHP 5.4, and scalar (integer, float, string and boolean) types since PHP 7.0.[69] PHP 7.0 also has type declarations for function return types, expressed by placing the type name after the list of parameters, preceded by a colon.[68] For example, the getAdder function from the earlier example could be annotated with types like so in PHP 7: 

function getAdder(int $x): Closure { return fn(int $y): int => $x + $y; } $adder = getAdder(8); echo $adder(2); // prints "10" echo $adder(null); // throws an exception because an incorrect type was passed $adder = getAdder([]); // would also throw an exception

By default, scalar type declarations follow weak typing principles. So, for example, if a parameter's type is int, PHP would allow not only integers, but also convertible numeric strings, floats or booleans to be passed to that function, and would convert them.[69] However, PHP 7 has a "strict typing" mode which, when used, disallows such conversions for function calls and returns within a file.[69]

PHP Objects

Basic object-oriented programming functionality was added in PHP 3 and improved in PHP 4.[10] This allowed for PHP to gain further abstraction, making creative tasks easier for programmers using the language. Object handling was completely rewritten for PHP 5, expanding the feature set and enhancing performance.[213] In previous versions of PHP, objects were handled like value types.[213] The drawback of this method was that code had to make heavy use of PHP's "reference" variables if it wanted to modify an object it was passed rather than creating a copy of it. In the new approach, objects are referenced by handle, and not by value.

PHP 5 introduced private and protected member variables and methods, along with abstract classes, final classes, abstract methods, and final methods. It also introduced a standard way of declaring constructors and destructors, similar to that of other object-oriented languages such as C++, and a standard exception handling model. Furthermore, PHP 5 added interfaces and allowed for multiple interfaces to be implemented. There are special interfaces that allow objects to interact with the runtime system. Objects implementing ArrayAccess can be used with array syntax and objects implementing Iterator or IteratorAggregate can be used with the foreach language construct. There is no virtual table feature in the engine, so static variables are bound with a name instead of a reference at compile time.[214]

If the developer creates a copy of an object using the reserved word clone, the Zend engine will check whether a __clone() method has been defined. If not, it will call a default __clone() which will copy the object's properties. If a __clone() method is defined, then it will be responsible for setting the necessary properties in the created object. For convenience, the engine will supply a function that imports the properties of the source object, so the programmer can start with a by-value replica of the source object and only override properties that need to be changed.[215]

The visibility of PHP properties and methods is defined using the keywords public, private, and protected. The default is public, if only var is used; var is a synonym for public. Items declared public can be accessed everywhere. protected limits access to inherited classes (and to the class that defines the item). private limits visibility only to the class that defines the item.[216] Objects of the same type have access to each other's private and protected members even though they are not the same instance.

Example

The following is a basic example of object-oriented programming in PHP 8: 

<?php  abstract class User {  protected string $name;   public function __construct(string $name)  {  // make first letter uppercase and the rest lowercase  $this->name = ucfirst(strtolower($name));  }   public function greet(): string  {  return "Hello, my name is " . $this->name;  }   abstract public function job(): string; }  class Student extends User {  public function __construct(string $name, private string $course)  {  parent::__construct($name);  }   public function job(): string  {  return "I learn " . $this->course;  } }  class Teacher extends User {  public function __construct(string $name, private array $teachingCourses)  {  parent::__construct($name);  }   public function job(): string  {  return "I teach " . implode(", ", $this->teachingCourses);  } }  $students = [  new Student("Alice", "Computer Science"),  new Student("Bob", "Computer Science"),  new Student("Charlie", "Business Studies"), ];  $teachers = [  new Teacher("Dan", ["Computer Science", "Information Security"]),  new Teacher("Erin", ["Computer Science", "3D Graphics Programming"]),  new Teacher("Frankie", ["Online Marketing", "Business Studies", "E-commerce"]), ];  foreach ([$students, $teachers] as $users) {  echo $users[0]::class . "s:\n";   array_walk($users, function (User $user) {  echo "{$user->greet()}, {$user->job()}\n";  }); }

This program outputs the following: 

Students: Hello, my name is Alice, I learn Computer Science Hello, my name is Bob, I learn Computer Science Hello, my name is Charlie, I learn Business Studies Teachers: Hello, my name is Dan, I teach Computer Science, Information Security Hello, my name is Erin, I teach Computer Science, 3D Graphics Programming Hello, my name is Frankie, I teach Online Marketing, Business Studies, E-commerce

Implementations

The only complete PHP implementation is the original, known simply as PHP. It is the most widely used and is powered by the Zend Engine. To disambiguate it from other implementations, it is sometimes unofficially called "Zend PHP". The Zend Engine compiles PHP source code on-the-fly into an internal format that it can execute, thus it works as an interpreter.[217][218] It is also the "reference implementation" of PHP, as PHP has no formal specification, and so the semantics of Zend PHP define the semantics of PHP. Due to the complex and nuanced semantics of PHP, defined by how Zend works, it is difficult for competing implementations to offer complete compatibility.

PHP's single-request-per-script-execution model, and the fact that the Zend Engine is an interpreter, leads to inefficiency; as a result, various products have been developed to help improve PHP performance. In order to speed up execution time and not have to compile the PHP source code every time the web page is accessed, PHP scripts can also be deployed in the PHP engine's internal format by using an opcode cache, which works by caching the compiled form of a PHP script (opcodes) in shared memory to avoid the overhead of parsing and compiling the code every time the script runs. An opcode cache, Zend Opcache, is built into PHP since version 5.5.[219] Another example of a widely used opcode cache is the Alternative PHP Cache (APC), which is available as a PECL extension.[220]

While Zend PHP is still the most popular implementation, several other implementations have been developed. Some of these are compilers or support JIT compilation, and hence offer performance benefits over Zend PHP at the expense of lacking full PHP compatibility. Alternative implementations include the following:

  • HHVM (HipHop Virtual Machine) – developed at Facebook and available as open source, it converts PHP code into a high-level bytecode (commonly known as an intermediate language), which is then translated into x86-64 machine code dynamically at runtime by a just-in-time (JIT) compiler, resulting in up to 6× performance improvements.[221] However, since version 7.2 Zend has outperformed HHVM,[222] and HHVM 3.24 is the last version to officially support PHP.[223]
    • HipHop – developed at Facebook and available as open source, it transforms the PHP scripts into C++ code and then compiles the resulting code, reducing the server load up to 50%. In early 2013, Facebook deprecated it in favor of HHVM due to multiple reasons, including deployment difficulties and lack of support for the whole PHP language, including the create_function() and eval() constructs.[224]
  • Parrot – a virtual machine designed to run dynamic languages efficiently; the cross-translator Pipp transforms the PHP source code into the Parrot intermediate representation, which is then translated into the Parrot's bytecode and executed by the virtual machine.
  • PeachPie – a second-generation compiler to .NET Common Intermediate Language (CIL) bytecode, built on the Roslyn platform; successor of Phalanger, sharing several architectural components
  • Phalanger – compiles PHP into .Net Common Intermediate Language bytecode; predecessor of PeachPie
  • Quercus – compiles PHP into Java bytecode

Licensing

Main article: PHP License

PHP is free software released under the PHP License, which stipulates that:[225]

Products derived from this software may not be called "PHP", nor may "PHP" appear in their name, without prior written permission from group@php.net. You may indicate that your software works in conjunction with PHP by saying "Foo for PHP" instead of calling it "PHP Foo" or "phpfoo".

This restriction on use of "PHP" makes the PHP License incompatible with the General Public License (GPL), while the Zend License is incompatible due to an advertising clause similar to that of the original BSD license.[226]

Development and community

PHP includes various free and open-source libraries in its source distribution, or uses them in resulting PHP binary builds. PHP is fundamentally an Internet-aware system with built-in modules for accessing File Transfer Protocol (FTP) servers and many database servers, including PostgreSQL, MySQL, Microsoft SQL Server and SQLite (which is an embedded database), LDAP servers, and others. Numerous functions familiar to C programmers, such as those in the stdio family, are available in standard PHP builds.[227]

PHP allows developers to write extensions in C to add functionality to the PHP language. PHP extensions can be compiled statically into PHP or loaded dynamically at runtime. Numerous extensions have been written to add support for the Windows API, process management on Unix-like operating systems, multibyte strings (Unicode), cURL, and several popular compression formats. Other PHP features made available through extensions include integration with Internet Relay Chat (IRC), dynamic generation of images and Adobe Flash content, PHP Data Objects (PDO) as an abstraction layer used for accessing databases,[228][229][230][231][232][233][234] and even speech synthesis. Some of the language's core functions, such as those dealing with strings and arrays, are also implemented as extensions.[235] The PHP Extension Community Library (PECL) project is a repository for extensions to the PHP language.[236]

Some other projects, such as Zephir, provide the ability for PHP extensions to be created in a high-level language and compiled into native PHP extensions. Such an approach, instead of writing PHP extensions directly in C, simplifies the development of extensions and reduces the time required for programming and testing.[237]

By December 2018 the PHP Group consisted of ten people: Thies C. Arntzen, Stig Bakken, Shane Caraveo, Andi Gutmans, Rasmus Lerdorf, Sam Ruby, Sascha Schumann, Zeev Suraski, Jim Winstead, and Andrei Zmievski.[238]

Zend Technologies provides a PHP Certification based on PHP 7[239] exam (and previously based on PHP 5.5) for programmers to become certified PHP developers.

PHP Foundation

On November 26, 2021, the JetBrains blog announced the creation of the PHP Foundation, which will sponsor the design and development of PHP.[240]

Installation and configuration

 
Example output of the phpinfo() function in PHP 7.1

There are two primary ways for adding support for PHP to a web server – as a native web server module, or as a CGI executable. PHP has a direct module interface called server application programming interface (SAPI), which is supported by many web servers including Apache HTTP Server, Microsoft IIS and iPlanet Web Server. Some other web servers, such as OmniHTTPd, support the Internet Server Application Programming Interface (ISAPI), which is Microsoft's web server module interface. If PHP has no module support for a web server, it can always be used as a Common Gateway Interface (CGI) or FastCGI processor; in that case, the web server is configured to use PHP's CGI executable to process all requests to PHP files.[241]

PHP-FPM (FastCGI Process Manager) is an alternative FastCGI implementation for PHP, bundled with the official PHP distribution since version 5.3.3.[242] When compared to the older FastCGI implementation, it contains some additional features, mostly useful for heavily loaded web servers.[243]

When using PHP for command-line scripting, a PHP command-line interface (CLI) executable is needed. PHP supports a CLI server application programming interface (SAPI) since PHP 4.3.0.[244] The main focus of this SAPI is developing shell applications using PHP. There are quite a few differences between the CLI SAPI and other SAPIs, although they do share many of the same behaviors.[245]

PHP has a direct module interface called SAPI for different web servers;[246] in case of PHP 5 and Apache 2.0 on Windows, it is provided in form of a DLL file called php5apache2.dll,[247] which is a module that, among other functions, provides an interface between PHP and the web server, implemented in a form that the server understands. This form is what is known as a SAPI.

There are different kinds of SAPIs for various web server extensions. For example, in addition to those listed above, other SAPIs for the PHP language include the Common Gateway Interface and command-line interface.[246][248]

PHP can also be used for writing desktop graphical user interface (GUI) applications, by using the PHP-GTK extension. PHP-GTK is not included in the official PHP distribution,[241] and as an extension it can be used only with PHP versions 5.1.0 and newer. The most common way of installing PHP-GTK is compiling it from the source code.[249]

When PHP is installed and used in cloud environments, software development kits (SDKs) are provided for using cloud-specific features. For example:

Numerous configuration options are supported, affecting both core PHP features and extensions.[252][253] Configuration file php.ini is searched for in different locations, depending on the way PHP is used.[254] The configuration file is split into various sections,[255] while some of the configuration options can be also set within the web server configuration.[256]

Use

 
A broad overview of the LAMP software bundle, displayed here together with Squid

PHP is a general-purpose scripting language that is especially suited to server-side web development, in which case PHP generally runs on a web server. Any PHP code in a requested file is executed by the PHP runtime, usually to create dynamic web page content or dynamic images used on websites or elsewhere.[257] It can also be used for command-line scripting and client-side graphical user interface (GUI) applications. PHP can be deployed on most web servers, many operating systems and platforms, and can be used with many relational database management systems (RDBMS). Most web hosting providers support PHP for use by their clients. It is available free of charge, and the PHP Group provides the complete source code for users to build, customize and extend for their own use.[16]

 
Dynamic web page: example of server-side scripting (PHP and MySQL)

Originally designed to create dynamic web pages, PHP now focuses mainly on server-side scripting,[258] and it is similar to other server-side scripting languages that provide dynamic content from a web server to a client, such as Microsoft's ASP.NET, Sun Microsystems' JavaServer Pages,[259] and mod_perl. PHP has also attracted the development of many software frameworks that provide building blocks and a design structure to promote rapid application development (RAD). Some of these include PRADO, CakePHP, Symfony, CodeIgniter, Laravel, Yii Framework, Phalcon and Laminas, offering features similar to other web frameworks.

The LAMP architecture has become popular in the web industry as a way of deploying web applications.[260] PHP is commonly used as the P in this bundle alongside Linux, Apache and MySQL, although the P may also refer to Python, Perl, or some mix of the three. Similar packages, WAMP and MAMP, are also available for Windows and macOS, with the first letter standing for the respective operating system. Although both PHP and Apache are provided as part of the macOS base install, users of these packages seek a simpler installation mechanism that can be more easily kept up to date.

For specific and more advanced usage scenarios, PHP offers a well defined and documented way for writing custom extensions in C or C++.[261][262][263][264][265][266][267] Besides extending the language itself in form of additional libraries, extensions are providing a way for improving execution speed where it is critical and there is room for improvements by using a true compiled language.[268][269] PHP also offers well defined ways for embedding itself into other software projects. That way PHP can be easily used as an internal scripting language for another project, also providing tight interfacing with the project's specific internal data structures.[270]

PHP received mixed reviews due to lacking support for multithreading at the core language level,[271] though using threads is made possible by the "pthreads" PECL extension.[272][273]

A command line interface, php-cli, and two ActiveX Windows Script Host scripting engines for PHP have been produced.

Popularity and usage statistics

PHP is used for Web content management systems including MediaWiki,[274] WordPress,[275] Joomla,[276] Drupal,[277] Moodle,[278] eZ Publish, eZ Platform, and SilverStripe.[279]

As of January 2013, PHP was used in more than 240 million websites (39% of those sampled) and was installed on 2.1 million web servers.[280]

As of March 2021, PHP was used as the server-side programming language on 79.1% of websites, down from 83.5% previously, where the language could be determined, and PHP 7 is the most used version of the language with 50.3% of all websites on the web using that version.[281]

Security

In 2019, 11% of all vulnerabilities listed by the National Vulnerability Database were linked to PHP;[282] historically, about 30% of all vulnerabilities listed since 1996 in this database are linked to PHP. Technical security flaws of the language itself or of its core libraries are not frequent (22 in 2009, about 1% of the total although PHP applies to about 20% of programs listed).[283] Recognizing that programmers make mistakes, some languages include taint checking to automatically detect the lack of input validation which induces many issues. Such a feature is being developed for PHP,[284] but its inclusion into a release has been rejected several times in the past.[285][286]

There are advanced protection patches such as Suhosin and Hardening-Patch, especially designed for web hosting environments.[287]

Historically, old versions of PHP had some configuration parameters and default values for such runtime settings that made some PHP applications prone to security issues. Among these, magic_quotes_gpc and register_globals[288] configuration directives were the best known; the latter made any URL parameters become PHP variables, opening a path for serious security vulnerabilities by allowing an attacker to set the value of any uninitialized global variable and interfere with the execution of a PHP script. Support for "magic quotes" and "register globals" settings has been deprecated since PHP 5.3.0, and removed from PHP 5.4.0.[289]

Another example for the potential runtime-settings vulnerability comes from failing to disable PHP execution (for example by using the engine configuration directive)[290] for the directory where uploaded files are stored; enabling it can result in execution of malicious code embedded within the uploaded files.[291][292][293] The best practice is to either locate the image directory outside of the document root available to the web server and serve it via intermediary script, or disable PHP execution for the directory which stores the uploaded files.

Also, enabling the dynamic loading of PHP extensions (via enable_dl configuration directive)[294] in a shared web hosting environment can lead to security issues.[295][296]

Implied type conversions that result in different values being treated as equal, sometimes against the programmer's intent, can lead to security issues. For example, the result of the comparison '0e1234' == '0' is true, because strings that are parsable as numbers are converted to numbers; in this case, the first compared value is treated as scientific notation having the value (0×101234), which is zero. Errors like this resulted in authentication vulnerabilities in Simple Machines Forum,[297] Typo3[298] and phpBB[299] when MD5 password hashes were compared. The recommended way is to use hash_equals() (for timing attack safety), strcmp or the identity operator (===), as '0e1234' === '0' results in false.[300]

In a 2013 analysis of over 170,000 website defacements, published by Zone-H, the most frequently (53%) used technique was exploitation of file inclusion vulnerability, mostly related to insecure usage of the PHP language constructs include, require, and allow_url_fopen.[301][302]

As of April 2021, W3Techs reports that 64% of websites using PHP, use versions 7.2 or older (which are no longer supported by The PHP Development Team) with 35% of all PHP websites using version 5.6 or older.[303]

Version 5 is still used by 24.5% of all the websites (September 2021).[304] It is highly recommended to migrate to PHP version 7 or 8 and use random_int() instead of rand() or mt_rand(), as the latter functions are not cryptographically-secure. There are two attacks that can be performed over PHP entropy sources: "seed attack" and "state recovery attack". With current GPU technologies an attacker can perform up to 230 MD5 calculations per second with a $250 GPU, while with an additional $500 can reach up to 232 calculations.[305] In combination with a "birthday attack" this can lead to serious security vulnerabilities.

See also

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Further reading

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  • Ford, Paul (June 11, 2015). "What is Code?". Bloomberg Businessweek. What's the Absolute Minimum I Must Know About PHP?

External links

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  • PHP at Curlie

January 13, 2023
this, article, about, scripting, language, other, uses, disambiguation, general, purpose, scripting, language, geared, toward, development, originally, created, danish, canadian, programmer, rasmus, lerdorf, 1993, released, 1995, reference, implementation, pro. This article is about the scripting language For other uses see PHP disambiguation PHP is a general purpose scripting language geared toward web development 7 It was originally created by Danish Canadian programmer Rasmus Lerdorf in 1993 and released in 1995 8 9 The PHP reference implementation is now produced by The PHP Group 10 PHP was originally an abbreviation of Personal Home Page 11 12 but it now stands for the recursive initialism PHP Hypertext Preprocessor 13 PHPParadigmMulti paradigm imperative functional object oriented procedural reflectiveDesigned byRasmus LerdorfDeveloperThe PHP Development Team Zend Technologies PHP FoundationFirst appearedJune 8 1995 27 years ago 1995 06 08 1 2 Stable release8 2 1 2023 01 05 3 Typing disciplineDynamic weak gradual 4 Implementation languageC primarily some components C OSUnix like Windows macOS IBM i OpenVMSLicensedual licensed GNU General Public License version 2 or any later version and PHP License for PHP versions 3 0 or earlier 5 Only PHP License most of Zend engine under Zend Engine License for 3 01x and later versions Filename extensions php phar phtml pht phpsWebsitewww wbr php wbr netMajor implementationsZend Engine HHVM PeachPie Quercus ParrotInfluenced byPerl HTML C C Java citation needed Tcl 2 JavaScript Hack 6 InfluencedHack JSP ASPPHP Programming at WikibooksPHP code is usually processed on a web server by a PHP interpreter implemented as a module a daemon or as a Common Gateway Interface CGI executable On a web server the result of the interpreted and executed PHP code which may be any type of data such as generated HTML or binary image data would form the whole or part of an HTTP response Various web template systems web content management systems and web frameworks exist which can be employed to orchestrate or facilitate the generation of that response Additionally PHP can be used for many programming tasks outside the web context such as standalone graphical applications 14 and robotic drone control 15 PHP code can also be directly executed from the command line The standard PHP interpreter powered by the Zend Engine is free software released under the PHP License PHP has been widely ported and can be deployed on most web servers on a variety of operating systems and platforms 16 The PHP language evolved without a written formal specification or standard until 2014 with the original implementation acting as the de facto standard which other implementations aimed to follow Since 2014 work has gone on to create a formal PHP specification 17 W3Techs reports that as of October 2022 update PHP is used by 74 4 of all the websites whose server side programming language we know 18 PHP version 7 4 is the most used version Support for version 7 3 was dropped on 6 December 2021 Contents 1 History 1 1 Early history 1 2 PHP 3 and 4 1 3 PHP 5 1 4 PHP 6 and Unicode 1 5 PHP 7 1 6 PHP 8 1 6 1 Just in time compilation 1 6 2 Addition of the match expression 1 6 3 Type changes and additions 1 6 4 Syntax changes and additions 1 6 5 Standard library changes and additions 1 6 6 Additional changes 1 7 PHP 8 1 1 7 1 Support for enumerations 1 7 2 Other PHP 8 1 features 1 8 PHP 8 2 1 9 Release history 2 Mascot 3 Syntax 3 1 Data types 3 2 Functions 3 3 PHP Objects 3 3 1 Example 4 Implementations 5 Licensing 6 Development and community 7 PHP Foundation 8 Installation and configuration 9 Use 9 1 Popularity and usage statistics 10 Security 11 See also 12 References 13 Further reading 14 External linksHistory Edit Rasmus Lerdorf creator of PHP and Andi Gutmans and Zeev Suraski creators of the Zend Engine Early history Edit PHP development began in 1993 8 when Rasmus Lerdorf wrote several Common Gateway Interface CGI programs in C 19 20 which he used to maintain his personal homepage He extended them to work with web forms and to communicate with databases and called this implementation Personal Home Page Forms Interpreter or PHP FI PHP FI could be used to build simple dynamic web applications To accelerate bug reporting and improve the code Lerdorf initially announced the release of PHP FI as Personal Home Page Tools PHP Tools version 1 0 on the Usenet discussion group comp infosystems www authoring cgi on June 8 1995 1 21 This release already had the basic functionality that PHP has today This included Perl like variables form handling and the ability to embed HTML The syntax resembled that of Perl but was simpler more limited and less consistent 10 An example of the early PHP syntax 22 lt include text header html gt lt getenv HTTP USER AGENT gt lt if substr exec result Mozilla gt Hey you are using Netscape lt p gt lt endif gt lt sql database select from table where user username gt lt ifless numentries 1 gt Sorry that record does not exist lt p gt lt endif exit gt Welcome lt user gt lt p gt You have lt index 0 gt credits left in your account lt p gt lt include text footer html gt Early PHP was not intended to be a new programming language and grew organically with Lerdorf noting in retrospect I don t know how to stop it there was never any intent to write a programming language I have absolutely no idea how to write a programming language I just kept adding the next logical step on the way 23 A development team began to form and after months of work and beta testing officially released PHP FI 2 in November 1997 The fact that PHP was not originally designed but instead was developed organically has led to inconsistent naming of functions and inconsistent ordering of their parameters 24 In some cases the function names were chosen to match the lower level libraries which PHP was wrapping 25 while in some very early versions of PHP the length of the function names was used internally as a hash function so names were chosen to improve the distribution of hash values 26 PHP 3 and 4 Edit This is an example of PHP code for the WordPress content management system Zeev Suraski and Andi Gutmans rewrote the parser in 1997 and formed the base of PHP 3 changing the language s name to the recursive acronym PHP Hypertext Preprocessor 10 27 Afterwards public testing of PHP 3 began and the official launch came in June 1998 Suraski and Gutmans then started a new rewrite of PHP s core producing the Zend Engine in 1999 28 They also founded Zend Technologies in Ramat Gan Israel 10 On 22 May 2000 PHP 4 powered by the Zend Engine 1 0 was released 10 By August 2008 this branch had reached version 4 4 9 PHP 4 is now no longer under development and nor are any security updates planned to be released 29 30 PHP 5 Edit On 1 July 2004 PHP 5 was released powered by the new Zend Engine II 10 PHP 5 included new features such as improved support for object oriented programming the PHP Data Objects PDO extension which defines a lightweight and consistent interface for accessing databases and numerous performance enhancements 31 In 2008 PHP 5 became the only stable version under development Late static binding had been missing from previous versions of PHP and was added in version 5 3 32 33 Many high profile open source projects ceased to support PHP 4 in new code from February 5 2008 because of the GoPHP5 initiative 34 provided by a consortium of PHP developers promoting the transition from PHP 4 to PHP 5 35 36 Over time PHP interpreters became available on most existing 32 bit and 64 bit operating systems either by building them from the PHP source code or by using pre built binaries 37 For PHP versions 5 3 and 5 4 the only available Microsoft Windows binary distributions were 32 bit IA 32 builds 38 39 requiring Windows 32 bit compatibility mode while using Internet Information Services IIS on a 64 bit Windows platform PHP version 5 5 made the 64 bit x86 64 builds available for Microsoft Windows 40 Official security support for PHP 5 6 ended on 31 December 2018 41 PHP 6 and Unicode Edit PHP received mixed reviews due to lacking native Unicode support at the core language level 42 43 In 2005 a project headed by Andrei Zmievski was initiated to bring native Unicode support throughout PHP by embedding the International Components for Unicode ICU library and representing text strings as UTF 16 internally 44 Since this would cause major changes both to the internals of the language and to user code it was planned to release this as version 6 0 of the language along with other major features then in development 45 However a shortage of developers who understood the necessary changes and performance problems arising from conversion to and from UTF 16 which is rarely used in a web context led to delays in the project 46 As a result a PHP 5 3 release was created in 2009 with many non Unicode features back ported from PHP 6 notably namespaces In March 2010 the project in its current form was officially abandoned and a PHP 5 4 release was prepared containing most remaining non Unicode features from PHP 6 such as traits and closure re binding 47 Initial hopes were that a new plan would be formed for Unicode integration but by 2014 none had been adopted PHP 7 Edit During 2014 and 2015 a new major PHP version was developed PHP 7 The numbering of this version involved some debate among internal developers 48 While the PHP 6 Unicode experiment had never been released several articles and book titles referenced the PHP 6 name which might have caused confusion if a new release were to reuse the name 49 After a vote the name PHP 7 was chosen 50 The foundation of PHP 7 is a PHP branch that was originally dubbed PHP next generation phpng It was authored by Dmitry Stogov Xinchen Hui and Nikita Popov 51 and aimed to optimize PHP performance by refactoring the Zend Engine while retaining near complete language compatibility 52 By 14 July 2014 WordPress based benchmarks which served as the main benchmark suite for the phpng project showed an almost 100 increase in performance Changes from phpng make it easier to improve performance in future versions as more compact data structures and other changes are seen as better suited for a successful migration to a just in time JIT compiler 53 Because of the significant changes the reworked Zend Engine was called Zend Engine 3 succeeding Zend Engine 2 used in PHP 5 54 Because of the major internal changes in phpng it must receive a new major version number of PHP rather than a minor PHP 5 release according to PHP s release process 55 Major versions of PHP are allowed to break backward compatibility of code and therefore PHP 7 presented an opportunity for other improvements beyond phpng that require backward compatibility breaks In particular it involved the following changes Many fatal or recoverable level legacy PHP error mechanisms were replaced with modern object oriented exceptions 56 The syntax for variable dereferencing was reworked to be internally more consistent and complete allowing the use of the operators gt and with arbitrary meaningful left side expressions 57 Support for legacy PHP 4 style constructor methods was deprecated 58 The behavior of the foreach statement was changed to be more predictable 59 Constructors for the few classes built in to PHP which returned null upon failure were changed to throw an exception instead for consistency 60 Several unmaintained or deprecated server application programming interfaces SAPIs and extensions were removed from the PHP core most notably the legacy mysql extension 61 The behavior of the list operator was changed to remove support for strings 62 Support was removed for legacy ASP style delimiters lt and gt and lt script language php gt lt script gt 63 An oversight allowing a switch statement to have multiple default clauses was fixed 64 Support for hexadecimal number support in some implicit conversions from strings to number types was removed 65 The left shift and right shift operators were changed to behave more consistently across platforms 66 Conversions between floating point numbers and integers were changed e g infinity changed to convert to zero and implemented more consistently across platforms 66 67 PHP 7 also included new language features Most notably it introduced return type declarations for functions 68 which complement the existing parameter type declarations and support for the scalar types integer float string and boolean in parameter and return type declarations 69 PHP 8 Edit PHP 8 was released on November 26 2020 PHP 8 is a major version and has breaking changes from previous versions 70 71 New features and notable changes include Just in time compilation Edit Just in time compilation is supported in PHP 8 72 PHP 8 s JIT compiler can provide substantial performance improvements for some use cases 73 74 while PHP developer Nikita Popov stated that the performance improvements for most websites will be less substantial than the upgrade from PHP 5 to PHP 7 75 Substantial improvements are expected more for mathematical type operations than for common web development use cases 75 Additionally the JIT compiler provides future potential to move some code from C to PHP due to the performance improvements for some use cases 76 Addition of the match expression Edit Main article PHP syntax and semantics Match expression PHP 8 introduced the match expression 77 The match expression is conceptually similar to a switch statement and is more compact for some use cases 78 Because match is an expression its result can be caught into a variable or returned from a function 79 Type changes and additions Edit PHP 8 introduced union types a new static return type and a new mixed type 70 Attributes often referred to as annotations in other programming languages were added in PHP 8 which allow metadata to be added to classes 70 throw was changed from being a statement to being an expression 80 This allows exceptions to be thrown in places that were not previously possible 70 Syntax changes and additions Edit PHP 8 includes changes to allow alternate more concise or more consistent syntaxes in a number of scenarios For example the nullsafe operator is similar to the null coalescing operator but used when calling methods 81 The following code snippet will not throw an error if getBirthday returns null human readable date user gt getBirthday gt diffForHumans Constructor property promotion has been added as syntactic sugar allowing class properties to be set automatically when parameters are passed into a class constructor 70 This reduces the amount of boilerplate code that must be written Other minor changes include support for use of class on objects which serves as an alternative for the use of get class 70 non capturing catches in try catch blocks variable syntax tweaks to resolve inconsistencies support for named arguments and support for trailing commas in parameter lists which adds consistency with support for trailing commas in other contexts such as in arrays Standard library changes and additions Edit Weak maps were added in PHP 8 A WeakMap holds references to objects but these references do not prevent such objects from being garbage collected 82 This can provide performance improvements in scenarios where data is being cached this is of particular relevance for object relational mappings ORM 70 Various adjustments to interfaces such as adding support for creating DateTime objects from interfaces and the addition of a Stringable interface that can be used for type hinting Various new functions including str contains str starts with and str ends with 83 fdiv get debug type and get resource id Object implementation of token get all Additional changes Edit Type annotations were also added into PHP s C source code itself to allow internal functions and methods to have complete type information in reflection 84 Inheritance with private methods Abstract methods in traits improvementsPHP 8 1 Edit PHP 8 1 was released on December 8 2021 and included a number of new features and improvements over previous versions Here is a more detailed look at some of the key features and improvements in PHP 8 1 Union types This feature allows you to specify that a variable can have multiple types such as an integer or a string This can be useful for writing more flexible and robust code as it allows you to handle a wider range of input values Nullsafe operator This operator allows you to chain method calls without worrying about null references For example if you want to call a method on an object that may be null you can use the nullsafe operator to ensure that the method is only called if the object is not null Match expression This is a more concise and flexible way to perform matching on values It allows you to specify multiple cases and their associated values and then use the match keyword to select the appropriate case based on the value of an expression Improved performance PHP 8 1 includes various performance improvements such as faster array operations and better memory usage These improvements can help make your code run faster and more efficiently New error handling features PHP 8 1 introduces a new throws keyword that allows you to specify which exceptions a function can throw and a new assert function that can be used to check for certain conditions at runtime These features can help you write more reliable and robust code Other new features PHP 8 1 also includes other new features such as support for named arguments support for attributes similar to annotations in other languages and improved support for Unicode 85 The match expression is a new feature in PHP 8 1 that allows you to perform value matching in a more concise and flexible way It is similar to a switch statement but with some additional features and syntax improvements Here is an example of how you can use the match expression in PHP value 3 result match value 0 gt The value is zero 1 2 3 gt The value is one two or three default gt The value is something else echo result Outputs The value is one two or three In this example the match expression compares the value of value to the different cases specified in the curly braces If value matches one of the cases the corresponding value is returned If none of the cases match the default case is used One of the main benefits of the match expression is that it allows you to specify multiple values for a single case as shown in the example above This can help make your code more concise and easier to read The match expression also allows you to specify a when clause for each case which can be used to specify additional conditions that must be met for the case to be matched For example value 3 result match value 0 gt The value is zero 1 2 3 when value gt 1 gt The value is two or three default gt The value is something else echo result Outputs The value is two or three Overall the match expression is a useful addition to PHP that can make it easier to write code that performs value matching and conditional processing Assert Error handlingThe assert function and the throws keyword are new error handling features in PHP 8 1 that can help you write more reliable and robust code The assert function is used to check for certain conditions at runtime If the condition is not met the function generates an AssertionError exception For example assert x gt 0 x must be greater than zero In this example the assert function checks whether x is greater than zero If it is not an AssertionError exception is thrown with the message x must be greater than zero The throws keyword on the other hand is used to specify which exceptions a function or method can throw This can be helpful for documenting your code and making it easier for other developers to understand how your functions and methods behave For example function divide int a int b int if b 0 throw new DivisionByZeroError Cannot divide by zero return a b In this example the divide function uses the throws keyword to specify that it can throw a DivisionByZeroError exception if the second argument is zero Overall the assert function and the throws keyword are useful tools for handling errors and exceptions in PHP and can help you write more reliable and robust code 86 Support for enumerations EditSupport for enumerations was one of the most prominent features of PHP 8 1 87 Enums allow developers to programmatically enforce states in their codebase Below is an example of an enum lt php namespace App Enums enum InvoiceStatus string case draft draft case pending pending case paid paid case expired expired Other PHP 8 1 features Edit Support for read only properties was added After the introduction of array unpacking in PHP 7 4 with consecutive numbered keys PHP 8 1 introduced support for array unpacking with string keys PHP 8 1 added support for using new in initializers A new syntax was added for creating callables PHP 8 1 brought support for Pure Intersection Types after in the introduction of union types in PHP 8 0 PHP 8 2 Edit PHP 8 2 includes a number of new features and improvements Here are some of the main ones Union Types Union types allow you to specify that a function or method parameter can accept multiple types separated by the symbol This can help to improve type safety and reduce the need for type juggling Nullsafe Operator The nullsafe operator gt allows you to chain method calls without having to check for null values at each step This can help to reduce the need for null checks and make your code more concise Match Expression The match expression allows you to perform pattern matching on values similar to a switch statement in other languages This can be a more concise and expressive way to handle multiple conditions Improved Type Variance PHP 8 2 introduces improved type variance for generic types allowing you to specify whether a generic type is covariant contravariant or invariant This can help to improve type safety and flexibility when working with generic types Performance Improvements PHP 8 2 includes various performance improvements including faster JIT compilation faster garbage collection and improved handling of large arrays These improvements can help to make PHP applications faster and more efficient Deprecations Some features have been deprecated in PHP 8 2 including the assert function when used with a string argument and the list construct with a single array element It s important to be aware of these deprecations if you are upgrading from an earlier version of PHP Here are some examples of features that have been deprecated in PHP 8 2 assert function with string argument The assert function can be used to perform runtime checks but it has been deprecated when used with a string argument Instead you should use the assert function with a boolean argument or an expression list construct with a single array element The list construct allows you to unpack the elements of an array into separate variables It has been deprecated when used with a single array element as this usage was considered confusing and error prone create function The create function function has been deprecated as it has been superseded by anonymous functions which are more flexible and easier to use mb ereg replace callback The mb ereg replace callback function has been deprecated as it has been superseded by the preg replace callback function which provides similar functionality and is more widely used New Random extensionThe Random extension provides a new object oriented API for generating random values in PHP It includes several classes Engine s that implement different algorithms for generating random numbers and storing their state within objects This allows for multiple independent seedable sequences which can be useful in certain contexts such as testing or simulation The Random Randomizer class provides a high level interface for using the engine s randomness to generate a random integer shuffle an array or string select random array keys and more This can be a convenient way to perform these common tasks without having to directly use the lower level engine classes It s worth noting that the Random extension is not enabled by default in PHP and you will need to install and enable it in your PHP environment in order to use its features You can find more information about the extension in the official PHP documentation 88 Release history Edit Version Release date Supported until 89 NotesOld version no longer maintained 1 0 8 June 1995 Officially called Personal Home Page Tools PHP Tools This is the first use of the name PHP 10 Old version no longer maintained 2 0 1 November 1997 Officially called PHP FI 2 0 This is the first release that could actually be characterised as PHP being a standalone language with many features that have endured to the present day Old version no longer maintained 3 0 6 June 1998 20 October 2000 89 Development moves from one person to multiple developers Zeev Suraski and Andi Gutmans rewrite the base for this version 10 Old version no longer maintained 4 0 22 May 2000 90 23 June 2001 89 Added more advanced two stage parse execute tag parsing system called the Zend engine 91 Old version no longer maintained 4 1 10 December 2001 92 12 March 2002 89 Introduced superglobals span class nv GET span span class nv POST span span class nv SESSION span etc 91 Old version no longer maintained 4 2 22 April 2002 93 6 September 2002 89 Disabled register globals by default Data received over the network is not inserted directly into the global namespace anymore closing possible security holes in applications 91 Old version no longer maintained 4 3 27 December 2002 94 31 March 2005 89 Introduced the command line interface CLI to supplement the CGI 91 95 Old version no longer maintained 4 4 11 July 2005 96 7 August 2008 89 Fixed a memory corruption bug which required breaking binary compatibility with extensions compiled against PHP version 4 3 x 97 Old version no longer maintained 5 0 13 July 2004 98 5 September 2005 89 Zend Engine II with a new object model 99 Old version no longer maintained 5 1 24 November 2005 100 24 August 2006 89 Performance improvements with introduction of compiler variables in re engineered PHP Engine 99 Added PHP Data Objects PDO as a consistent interface for accessing databases 101 Old version no longer maintained 5 2 2 November 2006 102 6 January 2011 89 Enabled the filter extension by default Native JSON support 99 Old version no longer maintained 5 3 30 June 2009 103 14 August 2014 89 Namespace support late static bindings jump label limited goto anonymous functions closures PHP archives phar garbage collection for circular references improved Windows support sqlite3 mysqlnd as a replacement for libmysql as underlying library for the extensions that work with MySQL fileinfo as a replacement for mime magic for better MIME support the Internationalization extension and deprecation of ereg extension Old version no longer maintained 5 4 1 March 2012 104 3 September 2015 89 Trait support short array syntax support Removed items register globals safe mode allow call time pass reference span class nb session register span span class p span span class nb session unregister span span class p span and span class nb session is registered span span class p span Built in web server 105 Several improvements to existing features performance and reduced memory requirements Old version no longer maintained 5 5 20 June 2013 106 10 July 2016 107 Support for generators finally blocks for exceptions handling OpCache based on Zend Optimizer bundled in official distribution 108 Old version no longer maintained 5 6 28 August 2014 109 31 December 2018 107 Constant scalar expressions variadic functions argument unpacking new exponentiation operator extensions of the use statement for functions and constants new phpdbg debugger as a SAPI module and other smaller improvements 110 6 x Not released Abandoned version of PHP that planned to include native Unicode support 111 112 Old version no longer maintained 7 0 3 December 2015 113 10 January 2019 55 Zend Engine 3 performance improvements 53 and 64 bit integer support on Windows 114 uniform variable syntax 57 AST based compilation process 115 added span class nx Closure span span class o span span class na call span span class p span 116 bitwise shift consistency across platforms 117 span class o span null coalesce operator 118 Unicode code point escape syntax 119 return type declarations 68 scalar type integer float string and boolean declarations 69 lt gt spaceship three way comparison operator 120 generator delegation 121 anonymous classes 122 simpler and more consistently available CSPRNG API 123 replacement of many remaining internal PHP errors with the more modern exceptions 56 and shorthand syntax for importing multiple items from a namespace 124 Old version no longer maintained 7 1 1 December 2016 1 December 2019 107 void return type 125 class constant visibility modifiers 126 Old version no longer maintained 7 2 30 November 2017 30 November 2020 107 Object parameter and return type declaration 127 Libsodium extension 128 abstract method overriding 129 parameter type widening 130 Old version no longer maintained 7 3 6 December 2018 131 6 December 2021 Flexible Heredoc and Nowdoc syntax 132 support for reference assignment and array deconstruction with list 133 PCRE2 support 134 hrtime function 135 Old version no longer maintained 7 4 28 November 2019 136 28 November 2022 Typed properties 2 0 137 preloading 138 null coalescing assignment operator 139 improve openssl random pseudo bytes 140 Weak References 82 FFI foreign function interface 141 always available hash extension 142 password hash registry 143 multibyte string splitting 144 reflection for references 145 unbundle ext wddx 146 new custom object serialization mechanism 147 Older version yet still maintained 8 0 26 November 2020 148 26 November 2023 Just In Time JIT compilation 72 arrays starting with a negative index 149 stricter saner language semantics validation for abstract trait methods 150 saner string to number comparisons 151 saner numeric strings 152 TypeError on invalid arithmetic bitwise operators 153 reclassification of various engine errors 154 consistent type errors for internal functions 155 fatal error for incompatible method signatures 156 locale independent float to string conversion 157 variable syntax tweaks 158 attributes 159 160 161 162 named arguments 163 match expression 164 constructor property promotion 165 union types 166 mixed type 167 static return type 168 nullsafe operator 81 non capturing catches 169 throw expression 80 JSON extension is always available 170 Older version yet still maintained 8 1 25 November 2021 171 25 November 2024 Explicit octal integer literal notation 172 enumerations 173 readonly properties 174 first class callable syntax 175 new in initializers 176 pure intersection types 177 never return type 178 final class constraints 179 fibers 180 Current stable version 8 2 8 December 2022 181 8 December 2025 Readonly classes 182 null false and true as stand alone types 183 184 locale independent case conversion 185 Future release 8 3 23 November 2023 186 23 November 2026Legend Old versionOlder version still maintainedLatest versionLatest preview versionFuture releaseBeginning on 28 June 2011 the PHP Development Team implemented a timeline for the release of new versions of PHP 55 Under this system at least one release should occur every month Once per year a minor release should occur which may include new features Every minor release should at least be supported for two years with security and bug fixes followed by at least one year of only security fixes for a total of a three year release process for every minor release No new features unless small and self contained are to be introduced into a minor release during the three year release process Mascot Edit The elePHPant PHP mascot The mascot of the PHP project is the elePHPant a blue elephant with the PHP logo on its side designed by Vincent Pontier 187 in 1998 188 The PHP letters were forming the shape of an elephant if viewed in a sideways angle 189 The elePHPant is sometimes differently colored when in plush toy form Many variations of this mascot have been made over the years Only the elePHPants based on the original design by Vincent Pontier are considered official by the community 190 These are collectible and some of them are extremely rare 191 Syntax EditMain article PHP syntax and semantics A Hello World application in PHP 7 4 running on its built in development server The following Hello World program is written in PHP code embedded in an HTML document lt DOCTYPE html gt lt html gt lt head gt lt title gt PHP Hello World program lt title gt lt head gt lt body gt lt php echo lt p gt Hello World lt p gt gt lt body gt lt html gt However as no requirement exists for PHP code to be embedded in HTML the simplest version of Hello World may be written like this with the closing tag span class cp gt span span class x span omitted as preferred in files containing pure PHP code 192 lt php echo Hello World The PHP interpreter only executes PHP code within its delimiters Anything outside of its delimiters is not processed by PHP although non PHP text is still subject to control structures described in PHP code The most common delimiters are span class cp lt php span to open and span class cp gt span span class x span to close PHP sections The shortened form span class o lt span also exists This short delimiter makes script files less portable since support for them can be disabled in the local PHP configuration and it is therefore discouraged 193 194 Conversely there is no recommendation against the echo short tag span class o lt span 195 Prior to PHP 5 4 0 this short syntax for span class k echo span only works with the short open tag configuration setting enabled while for PHP 5 4 0 and later it is always available 196 197 193 The purpose of all these delimiters is to separate PHP code from non PHP content such as JavaScript code or HTML markup 198 So the shortest Hello World program written in PHP is lt Hello World The first form of delimiters span class cp lt php span and span class cp gt span span class x span in XHTML and other XML documents creates correctly formed XML processing instructions 199 This means that the resulting mixture of PHP code and other markup in the server side file is itself well formed XML Variables are prefixed with a dollar symbol and a type does not need to be specified in advance PHP 5 introduced type declarations that allows functions to force their parameters to be objects of a specific class arrays interfaces or callback functions However before PHP 7 type declarations could not be used with scalar types such as integer or string 69 Below is an example of how PHP variables are declared and initialized lt php name John variable of string type being declared and initialized age 18 variable of integer type being declared and initialized height 5 3 variable of double type being declared and initialized echo name is height m tall n concatenating variables and strings echo name is age years old interpolating variables to string gt Unlike function and class names variable names are case sensitive Both double quoted and heredoc strings provide the ability to interpolate a variable s value into the string 200 PHP treats newlines as whitespace in the manner of a free form language and statements are terminated by a semicolon 201 PHP has three types of comment syntax span class cm span marks block and inline comments span class c1 span or span class c1 span are used for one line comments 202 The echo statement is one of several facilities PHP provides to output text In terms of keywords and language syntax PHP is similar to the C style syntax span class k if span conditions span class k for span and span class k while span loops and function returns are similar in syntax to languages such as C C C Java and Perl Data types Edit PHP is loosely typed It stores integers in a platform dependent range either as a 32 64 or 128 bit signed integer equivalent to the C language long type Unsigned integers are converted to signed values in certain situations which is different behavior to many other programming languages 203 Integer variables can be assigned using decimal positive and negative octal hexadecimal and binary notations Floating point numbers are also stored in a platform specific range They can be specified using floating point notation or two forms of scientific notation 204 PHP has a native Boolean type that is similar to the native Boolean types in Java and C Using the Boolean type conversion rules non zero values are interpreted as true and zero as false as in Perl and C 204 The null data type represents a variable that has no value NULL is the only allowed value for this data type 204 Variables of the resource type represent references to resources from external sources These are typically created by functions from a particular extension and can only be processed by functions from the same extension examples include file image and database resources 204 Arrays can contain elements of any type that PHP can handle including resources objects and even other arrays Order is preserved in lists of values and in hashes with both keys and values and the two can be intermingled 204 PHP also supports strings which can be used with single quotes double quotes nowdoc or heredoc syntax 205 The Standard PHP Library SPL attempts to solve standard problems and implements efficient data access interfaces and classes 206 Functions Edit PHP defines a large array of functions in the core language and many are also available in various extensions these functions are well documented in the online PHP documentation 207 However the built in library has a wide variety of naming conventions and associated inconsistencies as described under history above Custom functions may be defined by the developer function myAge int birthYear string calculate the age by subtracting the birth year from the current year yearsOld date Y birthYear return the age in a descriptive string return yearsOld yearsOld 1 year years echo I am currently myAge 1995 old As of 2023 the output of the above sample program is I am currently 28 years old In lieu of function pointers functions in PHP can be referenced by a string containing their name In this manner normal PHP functions can be used for example as callbacks or within function tables 208 User defined functions may be created at any time without being prototyped 207 208 Functions may be defined inside code blocks permitting a run time decision as to whether or not a function should be defined There is a function exists function that determines whether a function with a given name has already been defined Function calls must use parentheses with the exception of zero argument class constructor functions called with the PHP operator new in which case parentheses are optional Since PHP 4 0 1 create function a thin wrapper around eval allowed normal PHP functions to be created during program execution it was deprecated in PHP 7 2 and removed in PHP 8 0 209 in favor of syntax for anonymous functions or closures 210 that can capture variables from the surrounding scope which was added in PHP 5 3 Shorthand arrow syntax was added in PHP 7 4 211 function getAdder x return fn y gt x y adder getAdder 8 echo adder 2 prints 10 In the example above getAdder function creates a closure using passed argument span class nv x span the keyword use imports a variable from the lexical context which takes an additional argument span class nv y span and returns the created closure to the caller Such a function is a first class object meaning that it can be stored in a variable passed as a parameter to other functions etc 212 Unusually for a dynamically typed language PHP supports type declarations on function parameters which are enforced at runtime This has been supported for classes and interfaces since PHP 5 0 for arrays since PHP 5 1 for callables since PHP 5 4 and scalar integer float string and boolean types since PHP 7 0 69 PHP 7 0 also has type declarations for function return types expressed by placing the type name after the list of parameters preceded by a colon 68 For example the getAdder function from the earlier example could be annotated with types like so in PHP 7 function getAdder int x Closure return fn int y int gt x y adder getAdder 8 echo adder 2 prints 10 echo adder null throws an exception because an incorrect type was passed adder getAdder would also throw an exception By default scalar type declarations follow weak typing principles So for example if a parameter s type is int PHP would allow not only integers but also convertible numeric strings floats or booleans to be passed to that function and would convert them 69 However PHP 7 has a strict typing mode which when used disallows such conversions for function calls and returns within a file 69 PHP Objects Edit Basic object oriented programming functionality was added in PHP 3 and improved in PHP 4 10 This allowed for PHP to gain further abstraction making creative tasks easier for programmers using the language Object handling was completely rewritten for PHP 5 expanding the feature set and enhancing performance 213 In previous versions of PHP objects were handled like value types 213 The drawback of this method was that code had to make heavy use of PHP s reference variables if it wanted to modify an object it was passed rather than creating a copy of it In the new approach objects are referenced by handle and not by value PHP 5 introduced private and protected member variables and methods along with abstract classes final classes abstract methods and final methods It also introduced a standard way of declaring constructors and destructors similar to that of other object oriented languages such as C and a standard exception handling model Furthermore PHP 5 added interfaces and allowed for multiple interfaces to be implemented There are special interfaces that allow objects to interact with the runtime system Objects implementing ArrayAccess can be used with array syntax and objects implementing Iterator or IteratorAggregate can be used with the foreach language construct There is no virtual table feature in the engine so static variables are bound with a name instead of a reference at compile time 214 If the developer creates a copy of an object using the reserved word clone the Zend engine will check whether a clone method has been defined If not it will call a default clone which will copy the object s properties If a clone method is defined then it will be responsible for setting the necessary properties in the created object For convenience the engine will supply a function that imports the properties of the source object so the programmer can start with a by value replica of the source object and only override properties that need to be changed 215 The visibility of PHP properties and methods is defined using the keywords public private and protected The default is public if only var is used var is a synonym for public Items declared public can be accessed everywhere protected limits access to inherited classes and to the class that defines the item private limits visibility only to the class that defines the item 216 Objects of the same type have access to each other s private and protected members even though they are not the same instance Example Edit The following is a basic example of object oriented programming in PHP 8 lt php abstract class User protected string name public function construct string name make first letter uppercase and the rest lowercase this gt name ucfirst strtolower name public function greet string return Hello my name is this gt name abstract public function job string class Student extends User public function construct string name private string course parent construct name public function job string return I learn this gt course class Teacher extends User public function construct string name private array teachingCourses parent construct name public function job string return I teach implode this gt teachingCourses students new Student Alice Computer Science new Student Bob Computer Science new Student Charlie Business Studies teachers new Teacher Dan Computer Science Information Security new Teacher Erin Computer Science 3D Graphics Programming new Teacher Frankie Online Marketing Business Studies E commerce foreach students teachers as users echo users 0 class s n array walk users function User user echo user gt greet user gt job n This program outputs the following Students Hello my name is Alice I learn Computer Science Hello my name is Bob I learn Computer Science Hello my name is Charlie I learn Business Studies Teachers Hello my name is Dan I teach Computer Science Information Security Hello my name is Erin I teach Computer Science 3D Graphics Programming Hello my name is Frankie I teach Online Marketing Business Studies E commerceImplementations EditThe only complete PHP implementation is the original known simply as PHP It is the most widely used and is powered by the Zend Engine To disambiguate it from other implementations it is sometimes unofficially called Zend PHP The Zend Engine compiles PHP source code on the fly into an internal format that it can execute thus it works as an interpreter 217 218 It is also the reference implementation of PHP as PHP has no formal specification and so the semantics of Zend PHP define the semantics of PHP Due to the complex and nuanced semantics of PHP defined by how Zend works it is difficult for competing implementations to offer complete compatibility PHP s single request per script execution model and the fact that the Zend Engine is an interpreter leads to inefficiency as a result various products have been developed to help improve PHP performance In order to speed up execution time and not have to compile the PHP source code every time the web page is accessed PHP scripts can also be deployed in the PHP engine s internal format by using an opcode cache which works by caching the compiled form of a PHP script opcodes in shared memory to avoid the overhead of parsing and compiling the code every time the script runs An opcode cache Zend Opcache is built into PHP since version 5 5 219 Another example of a widely used opcode cache is the Alternative PHP Cache APC which is available as a PECL extension 220 While Zend PHP is still the most popular implementation several other implementations have been developed Some of these are compilers or support JIT compilation and hence offer performance benefits over Zend PHP at the expense of lacking full PHP compatibility Alternative implementations include the following HHVM HipHop Virtual Machine developed at Facebook and available as open source it converts PHP code into a high level bytecode commonly known as an intermediate language which is then translated into x86 64 machine code dynamically at runtime by a just in time JIT compiler resulting in up to 6 performance improvements 221 However since version 7 2 Zend has outperformed HHVM 222 and HHVM 3 24 is the last version to officially support PHP 223 HipHop developed at Facebook and available as open source it transforms the PHP scripts into C code and then compiles the resulting code reducing the server load up to 50 In early 2013 Facebook deprecated it in favor of HHVM due to multiple reasons including deployment difficulties and lack of support for the whole PHP language including the create function and eval constructs 224 Parrot a virtual machine designed to run dynamic languages efficiently the cross translator Pipp transforms the PHP source code into the Parrot intermediate representation which is then translated into the Parrot s bytecode and executed by the virtual machine PeachPie a second generation compiler to NET Common Intermediate Language CIL bytecode built on the Roslyn platform successor of Phalanger sharing several architectural components Phalanger compiles PHP into Net Common Intermediate Language bytecode predecessor of PeachPie Quercus compiles PHP into Java bytecodeLicensing EditMain article PHP License PHP is free software released under the PHP License which stipulates that 225 Products derived from this software may not be called PHP nor may PHP appear in their name without prior written permission from group php net You may indicate that your software works in conjunction with PHP by saying Foo for PHP instead of calling it PHP Foo or phpfoo This restriction on use of PHP makes the PHP License incompatible with the General Public License GPL while the Zend License is incompatible due to an advertising clause similar to that of the original BSD license 226 Development and community EditPHP includes various free and open source libraries in its source distribution or uses them in resulting PHP binary builds PHP is fundamentally an Internet aware system with built in modules for accessing File Transfer Protocol FTP servers and many database servers including PostgreSQL MySQL Microsoft SQL Server and SQLite which is an embedded database LDAP servers and others Numerous functions familiar to C programmers such as those in the stdio family are available in standard PHP builds 227 PHP allows developers to write extensions in C to add functionality to the PHP language PHP extensions can be compiled statically into PHP or loaded dynamically at runtime Numerous extensions have been written to add support for the Windows API process management on Unix like operating systems multibyte strings Unicode cURL and several popular compression formats Other PHP features made available through extensions include integration with Internet Relay Chat IRC dynamic generation of images and Adobe Flash content PHP Data Objects PDO as an abstraction layer used for accessing databases 228 229 230 231 232 233 234 and even speech synthesis Some of the language s core functions such as those dealing with strings and arrays are also implemented as extensions 235 The PHP Extension Community Library PECL project is a repository for extensions to the PHP language 236 Some other projects such as Zephir provide the ability for PHP extensions to be created in a high level language and compiled into native PHP extensions Such an approach instead of writing PHP extensions directly in C simplifies the development of extensions and reduces the time required for programming and testing 237 By December 2018 the PHP Group consisted of ten people Thies C Arntzen Stig Bakken Shane Caraveo Andi Gutmans Rasmus Lerdorf Sam Ruby Sascha Schumann Zeev Suraski Jim Winstead and Andrei Zmievski 238 Zend Technologies provides a PHP Certification based on PHP 7 239 exam and previously based on PHP 5 5 for programmers to become certified PHP developers PHP Foundation EditOn November 26 2021 the JetBrains blog announced the creation of the PHP Foundation which will sponsor the design and development of PHP 240 Installation and configuration Edit Example output of the phpinfo function in PHP 7 1 There are two primary ways for adding support for PHP to a web server as a native web server module or as a CGI executable PHP has a direct module interface called server application programming interface SAPI which is supported by many web servers including Apache HTTP Server Microsoft IIS and iPlanet Web Server Some other web servers such as OmniHTTPd support the Internet Server Application Programming Interface ISAPI which is Microsoft s web server module interface If PHP has no module support for a web server it can always be used as a Common Gateway Interface CGI or FastCGI processor in that case the web server is configured to use PHP s CGI executable to process all requests to PHP files 241 PHP FPM FastCGI Process Manager is an alternative FastCGI implementation for PHP bundled with the official PHP distribution since version 5 3 3 242 When compared to the older FastCGI implementation it contains some additional features mostly useful for heavily loaded web servers 243 When using PHP for command line scripting a PHP command line interface CLI executable is needed PHP supports a CLI server application programming interface SAPI since PHP 4 3 0 244 The main focus of this SAPI is developing shell applications using PHP There are quite a few differences between the CLI SAPI and other SAPIs although they do share many of the same behaviors 245 PHP has a direct module interface called SAPI for different web servers 246 in case of PHP 5 and Apache 2 0 on Windows it is provided in form of a DLL file called php5apache2 dll 247 which is a module that among other functions provides an interface between PHP and the web server implemented in a form that the server understands This form is what is known as a SAPI There are different kinds of SAPIs for various web server extensions For example in addition to those listed above other SAPIs for the PHP language include the Common Gateway Interface and command line interface 246 248 PHP can also be used for writing desktop graphical user interface GUI applications by using the PHP GTK extension PHP GTK is not included in the official PHP distribution 241 and as an extension it can be used only with PHP versions 5 1 0 and newer The most common way of installing PHP GTK is compiling it from the source code 249 When PHP is installed and used in cloud environments software development kits SDKs are provided for using cloud specific features For example Amazon Web Services provides the AWS SDK for PHP 250 Microsoft Azure can be used with the Windows Azure SDK for PHP 251 Numerous configuration options are supported affecting both core PHP features and extensions 252 253 Configuration file php ini is searched for in different locations depending on the way PHP is used 254 The configuration file is split into various sections 255 while some of the configuration options can be also set within the web server configuration 256 Use Edit A broad overview of the LAMP software bundle displayed here together with Squid PHP is a general purpose scripting language that is especially suited to server side web development in which case PHP generally runs on a web server Any PHP code in a requested file is executed by the PHP runtime usually to create dynamic web page content or dynamic images used on websites or elsewhere 257 It can also be used for command line scripting and client side graphical user interface GUI applications PHP can be deployed on most web servers many operating systems and platforms and can be used with many relational database management systems RDBMS Most web hosting providers support PHP for use by their clients It is available free of charge and the PHP Group provides the complete source code for users to build customize and extend for their own use 16 Dynamic web page example of server side scripting PHP and MySQL Originally designed to create dynamic web pages PHP now focuses mainly on server side scripting 258 and it is similar to other server side scripting languages that provide dynamic content from a web server to a client such as Microsoft s ASP NET Sun Microsystems JavaServer Pages 259 and a href Mod perl html title Mod perl mod perl a PHP has also attracted the development of many software frameworks that provide building blocks and a design structure to promote rapid application development RAD Some of these include PRADO CakePHP Symfony CodeIgniter Laravel Yii Framework Phalcon and Laminas offering features similar to other web frameworks The LAMP architecture has become popular in the web industry as a way of deploying web applications 260 PHP is commonly used as the P in this bundle alongside Linux Apache and MySQL although the P may also refer to Python Perl or some mix of the three Similar packages WAMP and MAMP are also available for Windows and macOS with the first letter standing for the respective operating system Although both PHP and Apache are provided as part of the macOS base install users of these packages seek a simpler installation mechanism that can be more easily kept up to date For specific and more advanced usage scenarios PHP offers a well defined and documented way for writing custom extensions in C or C 261 262 263 264 265 266 267 Besides extending the language itself in form of additional libraries extensions are providing a way for improving execution speed where it is critical and there is room for improvements by using a true compiled language 268 269 PHP also offers well defined ways for embedding itself into other software projects That way PHP can be easily used as an internal scripting language for another project also providing tight interfacing with the project s specific internal data structures 270 PHP received mixed reviews due to lacking support for multithreading at the core language level 271 though using threads is made possible by the pthreads PECL extension 272 273 A command line interface php cli and two ActiveX Windows Script Host scripting engines for PHP have been produced Popularity and usage statistics Edit PHP is used for Web content management systems including MediaWiki 274 WordPress 275 Joomla 276 Drupal 277 Moodle 278 eZ Publish eZ Platform and SilverStripe 279 As of January 2013 update PHP was used in more than 240 million websites 39 of those sampled and was installed on 2 1 million web servers 280 As of March 2021 update PHP was used as the server side programming language on 79 1 of websites down from 83 5 previously where the language could be determined and PHP 7 is the most used version of the language with 50 3 of all websites on the web using that version 281 Security EditIn 2019 11 of all vulnerabilities listed by the National Vulnerability Database were linked to PHP 282 historically about 30 of all vulnerabilities listed since 1996 in this database are linked to PHP Technical security flaws of the language itself or of its core libraries are not frequent 22 in 2009 about 1 of the total although PHP applies to about 20 of programs listed 283 Recognizing that programmers make mistakes some languages include taint checking to automatically detect the lack of input validation which induces many issues Such a feature is being developed for PHP 284 but its inclusion into a release has been rejected several times in the past 285 286 There are advanced protection patches such as Suhosin and Hardening Patch especially designed for web hosting environments 287 Historically old versions of PHP had some configuration parameters and default values for such runtime settings that made some PHP applications prone to security issues Among these a href Magic quotes html title Magic quotes magic quotes gpc a and register globals 288 configuration directives were the best known the latter made any URL parameters become PHP variables opening a path for serious security vulnerabilities by allowing an attacker to set the value of any uninitialized global variable and interfere with the execution of a PHP script Support for magic quotes and register globals settings has been deprecated since PHP 5 3 0 and removed from PHP 5 4 0 289 Another example for the potential runtime settings vulnerability comes from failing to disable PHP execution for example by using the engine configuration directive 290 for the directory where uploaded files are stored enabling it can result in execution of malicious code embedded within the uploaded files 291 292 293 The best practice is to either locate the image directory outside of the document root available to the web server and serve it via intermediary script or disable PHP execution for the directory which stores the uploaded files Also enabling the dynamic loading of PHP extensions via enable dl configuration directive 294 in a shared web hosting environment can lead to security issues 295 296 Implied type conversions that result in different values being treated as equal sometimes against the programmer s intent can lead to security issues For example the result of the comparison 0e1234 0 is true because strings that are parsable as numbers are converted to numbers in this case the first compared value is treated as scientific notation having the value 0 101234 which is zero Errors like this resulted in authentication vulnerabilities in Simple Machines Forum 297 Typo3 298 and phpBB 299 when MD5 password hashes were compared The recommended way is to use hash equals for timing attack safety a href Strcmp html class mw redirect title Strcmp strcmp a or the identity operator as 0e1234 0 results in false 300 In a 2013 analysis of over 170 000 website defacements published by Zone H the most frequently 53 used technique was exploitation of file inclusion vulnerability mostly related to insecure usage of the PHP language constructs include require and allow url fopen 301 302 As of April 2021 update W3Techs reports that 64 of websites using PHP use versions 7 2 or older which are no longer supported by The PHP Development Team with 35 of all PHP websites using version 5 6 or older 303 Version 5 is still used by 24 5 of all the websites September 2021 304 It is highly recommended to migrate to PHP version 7 or 8 and use random int instead of rand or mt rand as the latter functions are not cryptographically secure There are two attacks that can be performed over PHP entropy sources seed attack and state recovery attack With current GPU technologies an attacker can perform up to 230 MD5 calculations per second with a 250 GPU while with an additional 500 can reach up to 232 calculations 305 In combination with a birthday attack this can lead to serious security vulnerabilities See also Edit Computer programming portal Free and open source software portalComparison of programming languages List of AMP packages List of PHP accelerators List of PHP editors PEAR PHP Extension and Application Repository PHP accelerator Template processor XAMPP Free and open source cross platform web server solution stack package Zend ServerReferences Edit a b Lerdorf Rasmus June 8 1995 Announce Personal Home Page Tools PHP Tools Retrieved 7 June 2011 a b Lerdorf Rasmus 2007 04 26 PHP on Hormones history of PHP presentation by Rasmus Lerdorf given at the MySQL Conference in Santa Clara California The Conversations Network Archived from the original on 2019 01 06 Retrieved 2009 12 11 PHP 8 2 1 Released PHP Function arguments Manual secure php net PHP Release Archives museum museum php net Stogov Dmitry 2015 12 04 It s not a secret that some PHP7 optimization ideas came from HHVM LuaJIT and V8 Twitter PHP Hypertext Preprocessor www php net Retrieved 2020 02 12 a b Krill Paul 2013 11 18 Believe the hype PHP founder backs Facebook s HipHop technology InfoWorld Retrieved 2022 10 13 Announce Personal Home Page Tools PHP Tools groups google com Retrieved 2022 11 03 a b c d e f g h i History of PHP and related projects The PHP Group Retrieved 2008 02 25 History of PHP php net Olsson Mikael 2013 09 04 PHP Quick Scripting Reference Apress ISBN 978 1 4302 6284 8 PHP Manual Preface www php net Introduction What can PHP do PHP Manual Retrieved 2009 03 05 helicopter Port of node ar drone which allows user to control a Parrot AR Drone over PHP jolicode php ar drone JoliCode 2019 01 11 retrieved 2019 02 23 a b Embedding PHP in HTML O Reilly 2001 05 03 Retrieved 2008 02 25 Jackson Joab 2014 07 31 PHP gets a formal specification at last Computerworld IDG Usage statistics of PHP for websites W3Techs World Wide Web Technology Surveys W3Techs 26 April 2021 Retrieved 26 April 2021 Lerdorf Rasmus 2012 07 20 I wonder why people keep writing that PHP was ever written in Perl It never was php Twitter Retrieved 2014 09 04 Lerdorf Rasmus 2007 04 26 PHP on Hormones The Conversations Network Archived from the original mp3 on 2019 01 06 Retrieved 2009 06 22 Lerdorf 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be released before 2011 if indeed it is released at all PHP 7 moves full speed ahead 2014 10 31 Recent versions of PHP have been part of the 5 x release series but there will be no PHP 6 We re going to skip version 6 because years ago we had plans for a 6 but those plans were very different from what we re doing now Gutmans said Going right to version 7 avoids confusion News Archive 2018 PHP 7 2 9 Released php net 2018 08 16 Retrieved 2018 08 16 PHP rfc size t and int64 next php net Retrieved 16 December 2014 PHP rfc abstract syntax tree php net Retrieved 16 December 2014 PHP rfc closure apply php net Retrieved 16 December 2014 PHP rfc integer semantics php net Retrieved 16 December 2014 PHP rfc isset ternary php net Retrieved 16 December 2014 RFC Unicode Codepoint Escape Syntax 2014 11 24 Retrieved 2014 12 19 Combined Comparison Spaceship Operator php net Retrieved 2015 05 21 PHP RFC Generator Delegation php net Retrieved 2015 05 21 PHP RFC Anonymous Classes php net Retrieved 2015 05 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the most critical application flaws On new OWASP Top 10 IPSec pl Retrieved 2015 04 15 Usage Statistics and Market Share of PHP for Websites December 2020 w3techs com Retrieved 2020 12 08 Usage statistics of PHP Version 5 for websites Randomness Attacks Against PHP Applications Further reading EditListen to this article 35 minutes source source This audio file was created from a revision of this article dated 23 November 2011 2011 11 23 and does not reflect subsequent edits Audio help More spoken articles Ford Paul June 11 2015 What is Code Bloomberg Businessweek What s the Absolute Minimum I Must Know About PHP External links EditPHP at Wikipedia s sister projects Media from Commons Textbooks from Wikibooks Resources from Wikiversity Documentation from MediaWiki Official website PHP at Curlie Retrieved from https en wikipedia org w index php title PHP amp oldid 1132006264, wikipedia, wiki, book, books, library,

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