std::pair
| template<
class T1, |
||
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
|
| template< class T, class U >
constexpr bool enable_nonlocking_formatter_optimization<std::pair<T, U>> = |
(since C++23) | |
This specialization of std::enable_nonlocking_formatter_optimization enables efficient implementation of std::print and std::println for printing a pair object when both T and U enable it.
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) [edit] |
| (C++11) |
creates a tuple of lvalue references or unpacks a tuple into individual objects (function template) [edit] |