tuple_size Class <tuple>
Visual Studio 2015
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Reports the number of elements that a tuple contains.
// 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.
The template class has a member value that is an integral constant expression whose value is the extent of the tuple type Tuple.
#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
*/
Header: <tuple>
Namespace: std
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