Difference between revisions of "cpp/named req/Container"
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|{{c|a {{==}} b}} || convertible to bool || {{rev inl|until=c++14|noborder=true|{{c|1=a.size() == b.size() && | |{{c|a {{==}} b}} || convertible to bool || {{rev inl|until=c++14|noborder=true|{{c|1=a.size() == b.size() && | ||
| − | std::equal(a.begin(), a.end(), b.begin()}}<br>}}{{rev inl|since=c++14|noborder=true|{{c|std::equal(a.begin(), a.end(), b.begin(), b.end())}}<br>}} ||Pre: T must be {{named req|EqualityComparable}} || Constant<ref>always linear for {{lc|std::forward_list}}</ref> if {{tt|a.size() !{{=}} b.size()}}, linear otherwise<!-- LWG2257 --> | + | std::equal(a.begin(), a.end(), b.begin())}}<br>}}{{rev inl|since=c++14|noborder=true|{{c|std::equal(a.begin(), a.end(), b.begin(), b.end())}}<br>}} ||Pre: T must be {{named req|EqualityComparable}} || Constant<ref>always linear for {{lc|std::forward_list}}</ref> if {{tt|a.size() !{{=}} b.size()}}, linear otherwise<!-- LWG2257 --> |
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|{{c|a !{{=}} b}} || convertible to bool || {{c|!(a {{==}} b)}} || || Linear | |{{c|a !{{=}} b}} || convertible to bool || {{c|!(a {{==}} b)}} || || Linear | ||
Revision as of 11:01, 5 December 2020
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
-
Ccontainer type; -
Telement type; -
a,bobjects of typeC. -
rva prvalue expression of typeC.
Types
| name | type | notes |
|---|---|---|
value_type |
T | Eraseable |
reference |
T& | |
const_reference |
const T& | |
iterator |
iterator pointing to T | LegacyForwardIterator convertible to const_iterator
|
const_iterator |
constant iterator pointing to T | LegacyForwardIterator |
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 CopyInsertable Post: a == C(a) |
Linear | |
| C(rv)(since C++11) | C | moves rv |
Post: equal to to the value rv had before this construction | Constant[1] | |
| a = b | C& | destroys or copy-assigns all elements of a from elements of b |
Post: a == b | Linear | |
| a = rv | C& | destroys or move-assigns all elements of a from elements of rv |
Post: if a and rv do not refer the same object, a is equal to to the value rv had before this assignment | 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 | a.size() == b.size() && std::equal(a.begin(), a.end(), b.begin()) (until C++14)std::equal(a.begin(), a.end(), b.begin(), b.end()) (since C++14) |
Pre: T must be EqualityComparable | Constant[2] 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[1][3] | ||
| swap(a, b) | void | a.swap(b) | Constant[1] | ||
| a.size() | size_type | std::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 | |||||
| |||||
Given
-
iandj, objects of a container'siteratortype,
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.
Container data races
Other requirements
- C
- T
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 179 | C++98 | iterator and const_iterator types might be incomparable
|
required to be comparable |
| LWG 2263 | C++11 | resolution of LWG179 was accidently dropped in C++11 | restored |
| LWG 2839 | C++11 | self move assignment of standard containers was not allowed | allowed but the result is unspecifed |
