std::get(std::pair)

C++

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Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

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Algorithms library

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Numerics library

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Regular expressions library (C++11)

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Technical Specifications

Utilities library

Type support (basic types, RTTI, type traits)
Dynamic memory management
Error handling
Program utilities
Variadic functions
Library feature-test macros
Date and time
Function objects
initializer_list (C++11)
bitset
hash (C++11)
integer_sequence (C++14)
Relational operators (deprecated)
rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=
Comparisons (C++20)
strong_order weak_order partial_order strong_equal weak_equal	strong_ordering weak_ordering partial_ordering strong_equality weak_equality	is_eqis_neqis_ltis_lteqis_gtis_gteq
common_comparison_category
Common vocabulary types
pair tuple (C++11) apply (C++17) make_from_tuple (C++17)	optional (C++17) any (C++17) variant (C++17)
Swap, forward and move
swap
exchange (C++14)
forward (C++11)
move (C++11)
move_if_noexcept (C++11)
Elementary string conversions
to_chars (C++17)
from_chars (C++17)
chars_format (C++17)
Type operations
declval (C++11)
as_const (C++17)

std::pair

Member functions

pair::pair

pair::operator=

pair::swap

Non-member functions

make_pair

operator==operator!=operator<operator<=operator>operator>=

std::swap

get (C++11)

Deduction guides(C++17)

Helper classes

tuple_size (C++11)

tuple_element (C++11)

Defined in header <utility>
	(1)
template< size_t I, class T1, class T2 > typename std::tuple_element<I, std::pair<T1,T2> >::type& get( pair<T1, T2>& p ) noexcept;		(1)	(since C++11) (until C++14)
template< size_t I, class T1, class T2 > constexpr std::tuple_element_t<I, std::pair<T1,T2> >& get( pair<T1, T2>& p ) noexcept;		(1)	(since C++14)
		(2)
template< size_t I, class T1, class T2 > const typename std::tuple_element<I, std::pair<T1,T2> >::type& get( const pair<T1,T2>& p ) noexcept;			(2)	(since C++11) (until C++14)
template< size_t I, class T1, class T2 > constexpr const std::tuple_element_t<I, std::pair<T1,T2> >& get( const pair<T1,T2>& p ) noexcept;			(2)	(since C++14)
			(3)
template< size_t I, class T1, class T2 > typename std::tuple_element<I, std::pair<T1,T2> >::type&& get( std::pair<T1,T2>&& p ) noexcept;				(3)	(since C++11) (until C++14)
template< size_t I, class T1, class T2 > constexpr std::tuple_element_t<I, std::pair<T1,T2> >&& get( std::pair<T1,T2>&& p ) noexcept;				(3)	(since C++14)
template< size_t I, class T1, class T2 > constexpr const std::tuple_element_t<I, std::pair<T1,T2> >&& get( const std::pair<T1,T2>&& p ) noexcept;				(4)	(since C++17)
template <class T, class U> constexpr T& get(std::pair<T, U>& p) noexcept;				(5)	(since C++14)
template <class T, class U> constexpr const T& get(const std::pair<T, U>& p) noexcept;				(6)	(since C++14)
template <class T, class U> constexpr T&& get(std::pair<T, U>&& p) noexcept;				(7)	(since C++14)
template <class T, class U> constexpr const T&& get(const std::pair<T, U>&& p) noexcept;				(8)	(since C++17)
template <class T, class U> constexpr T& get(std::pair<U, T>& p) noexcept;				(9)	(since C++14)
template <class T, class U> constexpr const T& get(const std::pair<U, T>& p) noexcept;				(10)	(since C++14)
template <class T, class U> constexpr T&& get(std::pair<U, T>&& p) noexcept;				(11)	(since C++14)
template <class T, class U> constexpr const T&& get(const std::pair<U, T>&& p) noexcept;				(12)	(since C++17)

Extracts an element from the pair using tuple-like interface.

The index-based overloads (1-4) fail to compile if the index I is neither 0 nor 1.

The type-based overloads (5-12) fail to compile if the types T and U are the same.

Parameters

p

-

pair whose contents to extract

Return value

1-4) Returns a reference to p.first if I==0 and a reference to p.second if I==1.

5-8) Returns a reference to p.first.

9-12) Returns a reference to p.second.

Example

Run this code

#include <iostream>
#include <utility>

int main()
{
    auto p = std::make_pair(1, 3.14);
    std::cout << '(' << std::get<0>(p) << ", " << std::get<1>(p) << ")\n";
    std::cout << '(' << std::get<int>(p) << ", " << std::get<double>(p) << ")\n";
}

Output:

(1, 3.14)
(1, 3.14)

See also

std::get(std::tuple)	tuple accesses specified element (function template)
std::get(std::array)	accesses an element of an array (function template)
std::get(std::variant) (C++17)	reads the value of the variant given the index or the type (if the type is unique), throws on error (function template)