tuple_size Class <utility>

Wraps pair element count.

template<class Tuple>
struct tuple_size;

template<class T1, class T2>
struct tuple_size<pair<T1, T2>>
   : integral_constant<size_t, 2>

// size of const tuple
template<class Tuple>
struct tuple_size<const Tuple>;

// size of volatile tuple
template<class Tuple>
struct tuple_size<volatile Tuple>;

// size of const volatile tuple
template<class Tuple>
struct tuple_size<const volatile Tuple>;

T1

The type of the first pair element.

T2

The type of the second pair element.

The template is a specialization of the template class tuple_size Class <tuple>. It has a member value that is an integral constant expression whose value is 2.

 

#include <utility> 
#include <iostream> 

using namespace std;

typedef pair<int, double> MyPair;

int main()
{
    MyPair c0(0, 1.1);

    // display contents " 0 1.1" 
    cout << " " << get<0>(c0);
    cout << " " << get<1>(c0) << endl;

    // display size " 2" 
    cout << " " << tuple_size<MyPair>::value << endl;

}

/*
Output:
0 1.1
2
*/

Header: <utility>

Namespace: std

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