std::make_pair

Since C++20

Header: <utility>

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

# Declarations

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)

# Parameters

x, y: the values to construct the pair from

# Return value

std::pair<T1, T2>(x, y)

# Example

#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";
}

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
LWG 181	C++98	the parameter types were const-referencetypes, which made passing arrays impossible	changed thesetypes to value types