Defined in header <utility> | ||
---|---|---|
template< class T1, class T2 > std::pair<T1, T2> make_pair( T1 t, T2 u ); | (until C++11) | |
template< class T1, class T2 > std::pair<V1, V2> make_pair( T1&& t, T2&& u ); | (since C++11) (until C++14) | |
template< class T1, class T2 > constexpr std::pair<V1, V2> make_pair( T1&& t, T2&& u ); | (since C++14) |
Creates a std::pair
object, deducing the target type from the types of arguments.
The deduced types | (since C++11) |
t, u | - | the values to construct the pair from |
A std::pair
object containing the given values.
#include <iostream> #include <utility> #include <functional> 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)
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 |
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