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Difference between revisions of "cpp/named req/Container"

From cppreference.com
< cpp‎ | named req
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{{cpp/concept/navbar}}
 
{{cpp/concept/navbar}}
  
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A {{tt|Container}} is an object used to store other objects and taking care of the management of the memory used by the objects it contains.
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A {{tt|container}} is an object used to store other objects and taking care of the management of the memory used by the objects it contains.
  
 
===Requirements===
 
===Requirements===
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|{{c|C()}}||C||creates an empty container|| Post: C().empty() == true||Constant
 
|{{c|C()}}||C||creates an empty container|| Post: C().empty() == true||Constant
 
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|-
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|{{c|C(a)}}||C||create a copy of {{ttb|a}}||Pre: T must be {{concept|CopyInsertable}}<br/>Post: a == C(a)||Linear
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|{{c|C(a)}}||C||creates a copy of {{ttb|a}}||Pre: T must be {{concept|CopyInsertable}}<br/>Post: a == C(a)||Linear
 
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|-
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|{{c|a {{=}} b}}||C&||all elements of {{ttb|a}} are destroyed or move assigned to elements of b||Post: a == b||Linear
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|{{c|a {{=}} b}}||C&||destroys or move-assigns all elements of {{ttb|a}} to elements of {{ttb|b}}||Post: a == b||Linear
 
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|{{c|(&a)->~C()}}||void||destroy all elements and free all memory||  ||Linear
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|{{c|(&a)->~C()}}||void||destroys all elements of {{ttb|a}} and frees all memory||  ||Linear
 
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|-
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|{{c|a.begin()}}||(const_)iterator||Iterator to the first element|| ||Constant
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|{{c|a.begin()}}||(const_)iterator||Iterator to the first element of {{ttb|a}}|| ||Constant
 
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|-
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|{{c|a.end()}}||(const_)iterator||Iterator to one past the last element||  ||Constant
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|{{c|a.end()}}||(const_)iterator||Iterator to one past the last element of {{ttb|a}}||  ||Constant
 
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|{{c|a.cbegin()}}{{mark since c++11}}||const_iterator||{{c|const_cast<const C&>(a).begin()}}|| ||Constant
 
|{{c|a.cbegin()}}{{mark since c++11}}||const_iterator||{{c|const_cast<const C&>(a).begin()}}|| ||Constant
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|{{c|a !{{=}} b}} || convertible to bool || {{c|!(a {{==}} b)}} || || Linear
 
|{{c|a !{{=}} b}} || convertible to bool || {{c|!(a {{==}} b)}} || || Linear
 
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|-
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|{{c|a.swap(b)}} || void || exchanges the values of a and b ||  
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|{{c|a.swap(b)}} || void || exchanges the values of {{ttb|a}} and {{ttb|b}} ||  
 
| Constant<ref name="array">{{mark since c++11}} Linear for {{lc|std::array}}</ref><ref name="should">{{mark until c++11}} Not strictly constant</ref>
 
| Constant<ref name="array">{{mark since c++11}} Linear for {{lc|std::array}}</ref><ref name="should">{{mark until c++11}} Not strictly constant</ref>
 
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|{{c|a.size()}} || size_type || {{c|distance(a.begin(), a.end())}} || || Constant<ref name="should" />
 
|{{c|a.size()}} || size_type || {{c|distance(a.begin(), a.end())}} || || Constant<ref name="should" />
 
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|{{c|a.max_size()}} || size_type || b.size() where b is the largest possible container || || Constant<ref name="should" />
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|{{c|a.max_size()}} || size_type || {{c|b.size()}} where {{ttb|b}} is the largest possible container || || Constant<ref name="should" />
 
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|{{c|a.empty()}} || convertible to bool || {{c|a.begin() {{==}} a.end()}} || || Constant
 
|{{c|a.empty()}} || convertible to bool || {{c|a.begin() {{==}} a.end()}} || || Constant

Revision as of 02:08, 3 February 2016

Template:cpp/concept/title Template:cpp/concept/navbar

A container is an object used to store other objects and taking care of the management of the memory used by the objects it contains.

Contents

Requirements

  • C container type;
  • T element type;
  • a, b objects of type C.

Types

name type notes
value_type T Template:concept
reference T&
const_reference const T&
iterator iterator pointing to T Template:concept
convertible to const_iterator
const_iterator const iterator pointing to T Template:concept
difference_type signed integer must be the same as iterator_traits::difference_type for iterator and const_iterator
size_type unsigned integer large enough to represent all positive values of difference_type

Methods and operators

expression return type semantics conditions complexity
C() C creates an empty container Post: C().empty() == true Constant
C(a) C creates a copy of a Pre: T must be Template:concept
Post: a == C(a)		 Linear
a = b C& destroys or move-assigns all elements of a to elements of b Post: a == b Linear
(&a)->~C() void destroys all elements of a and frees all memory Linear
a.begin() (const_)iterator Iterator to the first element of a Constant
a.end() (const_)iterator Iterator to one past the last element of a Constant
a.cbegin()(since C++11) const_iterator const_cast<const C&>(a).begin() Constant
a.cend()(since C++11) const_iterator const_cast<const C&>(a).end() Constant
a == b convertible to bool std::equal(a.begin(), a.end(), b.begin(), b.end())(since C++14) Pre: T must be Template:concept Constant[1] if a.size() != b.size(), linear otherwise
a != b convertible to bool !(a == b) Linear
a.swap(b) void exchanges the values of a and b Constant[2][3]
swap(a, b) void a.swap(b) Constant[2]
a.size() size_type distance(a.begin(), a.end()) Constant[3]
a.max_size() size_type b.size() where b is the largest possible container Constant[3]
a.empty() convertible to bool a.begin() == a.end() Constant
notes
  1. ↑ always linear for std::forward_list
  2. ↑ 2.0 2.1 (since C++11) Linear for std::array
  3. ↑ 3.0 3.1 3.2 (until C++11) Not strictly constant

Given

  • i and j, objects of a container's iterator type,

in the expressions i == j, i != j, i < j, i <= j, i >= j, i > j, i - j, either or both may be replaced by an object of the container's const_iterator type referring to the same element with no change in semantics.

(since C++14)

Container data races

see container thread safety

Other concepts

C
T
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