In computer science, a container is a class or a data structure[1][2] whose instances are collections of other objects. In other words, they store objects in an organized way that follows specific access rules.
The size of the container depends on the number of objects (elements) it contains. Underlying (inherited) implementations of various container types may vary in size, complexity and type of language, but in many cases they provide flexibility in choosing the right implementation for any given scenario.
Containers can be characterized by the following three properties:
access, that is the way of accessing the objects of the container. In the case of arrays, access is done with the array index. In the case of stacks, access is done according to the LIFO (last in, first out) order and in the case of queues it is done according to the FIFO (first in, first out) order;
storage, that is the way of storing the objects of the container;
traversal, that is the way of traversing the objects of the container.
Container classes are expected to implement CRUD-like methods to do the following:
create an empty container (constructor);
insert objects into the container;
delete objects from the container;
delete all the objects in the container (clear);
access the objects in the container;
access the number of objects in the container (count).
Containers are sometimes implemented in conjunction with iterators.
Typesedit
Containers may be classified as either single-value containers or associative containers.
Single-value containers store each object independently. Objects may be accessed directly, by a language loop construct (e.g. for loop) or with an iterator.
An associative container uses an associative array, map, or dictionary, composed of key-value pairs, such that each key appears at most once in the container. The key is used to find the value, the object, if it is stored in the container. Associative containers are used in programming languages as class templates.
Widget toolkits also use containers, which are special widgets to group other widgets, such as windows, panels. Apart from their graphical properties, they have the same type of behavior as container classes, as they keep a list of their child widgets, and allow adding, removing, or retrieving widgets among their children.
Container abstractions can be written in virtually any programming language, regardless of its type system.[3]: 273 However, in strongly-typedobject-oriented programming languages it may be somewhat complicated for a developer to write reusable homogeneous containers.
Because of differences in element types this results in a tedious process of writing and keeping a collection of containers for every elemental type.[3]: 274–276
Many elemental types (e.g. integers or floating numbers) are inherently incompatible with each other because of the memory size they occupy and their semantic meaning and therefore require different containers (unless of course, they are mutually compatible or convertible).[3]: 274–276 Modern programming languages offer various approaches to help solve the problem:[3]: 274–281
Universal basic type
A type that is universally assignable by any other (e.g. root Object class).
Permits storing types of different data sizes; it is hard to ensure which type is stored in a union upon retrieval however and should be carefully followed.
Ensures reusability and type safety; may be thought as a reverse inheritance. However, this approach may require implementing a template specialization which is reputedly a time-consuming process given that types differ in their methods.[3]: 281
^ abcdeBudd, Timothy (1997). An introduction to object-oriented programming (2nd ed.). Reading, Mass.: Addison-Wesley. ISBN0-201-82419-1. OCLC 34788238.
External linksedit
Container Data Structure Declaration and Initialization
January 01, 1970
container, abstract, data, type, container, computer, science, redirects, here, abstract, notion, containers, type, theory, container, type, theory, other, uses, container, disambiguation, this, article, require, cleanup, meet, wikipedia, quality, standards, s. Container computer science redirects here For the abstract notion of containers in type theory see Container type theory For other uses see Container disambiguation This article may require cleanup to meet Wikipedia s quality standards The specific problem is text is clunky Please help improve this article if you can March 2012 Learn how and when to remove this message In computer science a container is a class or a data structure 1 2 whose instances are collections of other objects In other words they store objects in an organized way that follows specific access rules The size of the container depends on the number of objects elements it contains Underlying inherited implementations of various container types may vary in size complexity and type of language but in many cases they provide flexibility in choosing the right implementation for any given scenario Container data structures are commonly used in many types of programming languages Contents 1 Function and properties 2 Types 3 Graphic containers 4 In statically typed languages 5 See also 6 References 7 External linksFunction and properties editContainers can be characterized by the following three properties access that is the way of accessing the objects of the container In the case of arrays access is done with the array index In the case of stacks access is done according to the LIFO last in first out order and in the case of queues it is done according to the FIFO first in first out order storage that is the way of storing the objects of the container traversal that is the way of traversing the objects of the container Container classes are expected to implement CRUD like methods to do the following create an empty container constructor insert objects into the container delete objects from the container delete all the objects in the container clear access the objects in the container access the number of objects in the container count Containers are sometimes implemented in conjunction with iterators Types editContainers may be classified as either single value containers or associative containers Single value containers store each object independently Objects may be accessed directly by a language loop construct e g for loop or with an iterator An associative container uses an associative array map or dictionary composed of key value pairs such that each key appears at most once in the container The key is used to find the value the object if it is stored in the container Associative containers are used in programming languages as class templates Container abstract data types include FIFO queues LIFO stacks Priority queues Lookup tables LUTs Key associated data structures Sets containing and indexing objects by value or by specific property Maps associating to each key a value for lookup Common data structures used to implement these abstract types include Arrays and their derivatives Linked lists Binary search trees BSTs particularly self balancing BSTs Hash tablesGraphic containers editWidget toolkits also use containers which are special widgets to group other widgets such as windows panels Apart from their graphical properties they have the same type of behavior as container classes as they keep a list of their child widgets and allow adding removing or retrieving widgets among their children In statically typed languages editSee also Statically typed programming language and Strong and weak typing Container abstractions can be written in virtually any programming language regardless of its type system 3 273 However in strongly typed object oriented programming languages it may be somewhat complicated for a developer to write reusable homogeneous containers Because of differences in element types this results in a tedious process of writing and keeping a collection of containers for every elemental type 3 274 276 Many elemental types e g integers or floating numbers are inherently incompatible with each other because of the memory size they occupy and their semantic meaning and therefore require different containers unless of course they are mutually compatible or convertible 3 274 276 Modern programming languages offer various approaches to help solve the problem 3 274 281 Universal basic type A type that is universally assignable by any other e g root Object class Downcasting Class substitution Previous three approaches above are used for weakly typed languages these usually imply inheritance and polymorphism shared by types Union types C C language Permits storing types of different data sizes it is hard to ensure which type is stored in a union upon retrieval however and should be carefully followed Type conversion Templates or Generics Ensures reusability and type safety may be thought as a reverse inheritance However this approach may require implementing a template specialization which is reputedly a time consuming process given that types differ in their methods 3 281 dd See also editList of data structures Standard Template Library Containers Collection abstract data type Java ConcurrentMapReferences edit Paul E Black ed entry for data structure in Dictionary of Algorithms and Data Structures US National Institute of Standards and Technology 15 December 2004 Accessed 4 Oct 2011 Entry data structure in the Encyclopaedia Britannica 2009 Online entry Accessed 4 Oct 2011 a b c d e Budd Timothy 1997 An introduction to object oriented programming 2nd ed Reading Mass Addison Wesley ISBN 0 201 82419 1 OCLC 34788238 External links editContainer Data Structure Declaration and Initialization Retrieved from https en wikipedia org w index php title Container abstract data type amp oldid 1223689900, wikipedia, wiki, book, books, library,
