std::pair - cppreference.com

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`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.

Template parameters

T1, T2

the types of the elements that the pair stores.

Member types

Member type	Definition
`first_type`	`T1`
`second_type`	`T2`

Member objects

Member name	Type
`first`	`T1`
`second`	`T2`

Member functions

Non-member functions

Helper classes

Helper specializations

`template< class T, class U > constexpr bool enable_nonlocking_formatter_optimization<std::pair<T, U>> = enable_nonlocking_formatter_optimization<T> && enable_nonlocking_formatter_optimization<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.

Deduction guides(since C++17)

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 2796	C++98	triviality of the destructor of `pair` was unspecified	specified

	implements fixed size container, which holds elements of possibly different types (class template) [edit]
	creates a std::tuple of lvalue references or unpacks a tuple into individual objects (function template) [edit]