Defined in header <utility> | ||
|---|---|---|
template<
class T1,
class T2
> struct pair;
|
std::pair is a class template that provides a way to store two heterogeneous objects as a single unit. A pair is a specific case of a std::tuple with two elements.
If neither T1 nor T2 is a possibly cv-qualified class type with non-trivial destructor, or array thereof, the destructor of pair is trivial.
| T1, T2 | - | the types of the elements that the pair stores. |
| Member type | Definition |
|---|---|
first_type | T1 |
second_type | T2 |
| Member name | Type |
|---|---|
first | T1 |
second | T2 |
| constructs new pair (public member function) |
|
| assigns the contents (public member function) |
|
|
(C++11) | swaps the contents (public member function) |
creates a pair object of type, defined by the argument types (function template) |
|
|
(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(removed in C++20)(C++20) | lexicographically compares the values in the pair (function template) |
|
(C++11) | specializes the std::swap algorithm (function template) |
|
(C++11) | accesses an element of a pair (function template) |
|
(C++11) | obtains the size of a pair (class template specialization) |
|
(C++11) | obtains the type of the elements of pair (class template specialization) |
|
(C++23) | determines the common reference type of two pairs (class template specialization) |
|
(C++23) | determines the common type of two pairs (class template specialization) |
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2796 | C++98 | triviality of the destructor of pair was unspecified | specified |
|
(C++11) | implements fixed size container, which holds elements of possibly different types (class template) |
|
(C++11) | creates a tuple of lvalue references or unpacks a tuple into individual objects (function template) |
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