tuple_size Class <tuple>
The latest version of this topic can be found at tuple_size Class;.
Reports the number of elements that a tuple contains.
Syntax
// TEMPLATE STRUCT tuple_size
template <class Tuple>
struct tuple_size;
// size of tuple
template <class... Types>
struct tuple_size<tuple<Types...>>
: integral_constant<size_t, sizeof...(Types)>;
// 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
Tuple
The type of the tuple.
Remarks
The template class has a member value that is an integral constant expression whose value is the extent of the tuple type Tuple.
Example
#include <tuple>
#include <iostream>
using namespace std;
typedef tuple<int, double, int, double> MyTuple;
int main()
{
MyTuple c0(0, 1.5, 2, 3.7);
// display contents " 0 1 2 3"
cout << " " << get<0>(c0);
cout << " " << get<1>(c0);
cout << " " << get<2>(c0);
cout << " " << get<3>(c0) << endl;
// display size " 4"
cout << " " << tuple_size<MyTuple>::value << endl;
}
/*
Output:
0 1.5 2 3.7
4
*/
Requirements
Header: <tuple>
Namespace: std