std::make_pair

 

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std::pair

Member functions

pair::pair

pair::operator=

pair::swap (C++11)

Non-member functions

make_pair

operator==operator!=operator<operator<=operator>operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

swap(std::pair) (C++11)

get(std::pair) (C++11)

Helper classes

tuple_size<std::pair> (C++11)

tuple_element<std::pair> (C++11)

basic_common_reference<std::pair> (C++23)

common_type<std::pair> (C++23)

formatter<std::pair> (C++23)

piecewise_construct_t (C++11)

Deduction guides(C++17)

 

Defined in header <utility>
template< class T1, class T2 > std::pair<T1, T2> make_pair( T1 x, T2 y );		(until C++11)
template< class T1, class T2 > std::pair</*V1*/, /*V2*/> make_pair( T1&& x, T2&& y );		(since C++11) (constexpr since C++14) (until C++20)
template< class T1, class T2 > constexpr std::pair<std::unwrap_ref_decay_t<T1>, std::unwrap_ref_decay_t<T2>> make_pair( T1&& x, T2&& y );		(since C++20)

Creates a std::pair object, deducing the target type from the types of arguments.

Given types std::decay<T1>::type as U1 and std::decay<T2>::type as U2, the types /*V1*/ and /*V2*/ are defined as follows: If U1 is std::reference_wrapper<X>, /*V1*/ is X&; otherwise /*V1*/ is U1. If U2 is std::reference_wrapper<Y>, /*V2*/ is Y&; otherwise /*V2*/ is U2.

(since C++11) (until C++20)

Parameters

x, y

-

the values to construct the pair from

Return value

std::pair<T1, T2>(x, y)	(until C++11)
std::pair</*V1*/, /*V2*/>(std::forward<T1>(x), std::forward<T2>(y))	(since C++11) (until C++20)
std::pair<std::unwrap_ref_decay_t<T1>, std::unwrap_ref_decay_t<T2>> (std::forward<T1>(x), std::forward<T2>(y))	(since C++20)

Example

Run this code

#include <functional>
#include <iostream>
#include <utility>

int main()
{
    int n = 1;
    int a[5] = {1, 2, 3, 4, 5};
    
    // build a pair from two ints
    auto p1 = std::make_pair(n, a[1]);
    std::cout << "The value of p1 is "
              << '(' << p1.first << ", " << p1.second << ")\n";
    
    // build a pair from a reference to int and an array (decayed to pointer)
    auto p2 = std::make_pair(std::ref(n), a);
    n = 7;
    std::cout << "The value of p2 is "
              << '(' << p2.first << ", " << *(p2.second + 2) << ")\n";
}

Output:

The value of p1 is (1, 2)
The value of p2 is (7, 3)

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 181	C++98	the parameter types were const-reference types, which made passing arrays impossible	changed these types to value types