tuple_size Class <utility>

2018-01-02

The latest version of this topic can be found at Visual Studio 2017 Documentation.

Wraps pair element count.

Syntax

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>;

Parameters

T1
The type of the first pair element.

T2
The type of the second pair element.

Remarks

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

Example

#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  
*/

Requirements

Header: <utility>

Namespace: std

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