std::tuple_size<std::tuple>
cppreference.com
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template< class... Types > struct tuple_size< std::tuple<Types...> > : std::integral_constant<std::size_t, sizeof...(Types)> { }; |
( C++11) | |
tuple .
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template< class T > inline constexpr std::size_t tuple_size_v = tuple_size<T>::value; |
( C++17) | |
std::integral_constant
value [static] |
sizeof...(Types) (public static -) |
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operator std::size_t |
std::size_t, value (public -) |
operator() (C++14) |
value (public -) |
value_type
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std::size_t
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type
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std::integral_constant<std::size_t, value>
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#include <iostream>
#include <tuple>
template <class T>
void test(T value)
{
int a[std::tuple_size_v<T>]; //
std::cout << std::tuple_size<T>{} << ' ' //
<< sizeof a << ' '
<< sizeof value << '\n';
}
int main()
{
test(std::make_tuple(1, 2, 3.14));
}
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| (C++17) | |
(C++11) |
tuple ( ) |
(C++11) |
( ) |