std::get(std::tuple)

 

C++

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template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type&     get( tuple<Types...>& t );	(1)	(since C++11) (until C++14)
template< std::size_t I, class... Types > constexpr typename std::tuple_element<I, tuple<Types...> >::type&     get( tuple<Types...>& t );	(1)	(since C++14)
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type&&     get( tuple<Types...>&& t );	(2)	(since C++11) (until C++14)
template< std::size_t I, class... Types > constexpr typename std::tuple_element<I, tuple<Types...> >::type&&     get( tuple<Types...>&& t );	(2)	(since C++14)
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type const&     get( const tuple<Types...>& t );	(3)	(since C++11) (until C++14)
template< std::size_t I, class... Types > constexpr typename std::tuple_element<I, tuple<Types...> >::type const&     get( const tuple<Types...>& t );	(3)	(since C++14)
template< class T, class... Types > constexpr T& get(tuple<Types...>& t);	(4)	(since C++14)
template< class T, class... Types > constexpr T&& get(tuple<Types...>&& t);	(5)	(since C++14)
template< class T, class... Types > constexpr const T& get(const tuple<Types...>& t);	(6)	(since C++14)

1-3) Extracts the Ith element from the tuple. I is an integer value in [0, sizeof...(Types)).

4-6) Extracts the element of the tuple t whose type is T. Fails to compile if the tuple has more than one element of that type.

Parameters

t

-

tuple whose contents to extract

Return value

1,4) Reference to the selected element of t.

2,5) Rvalue reference to the selected element of t, unless the element is of lvalue reference type, in which case lvalue reference is returned.

3,6) Const reference to the selected element of t.

Exceptions

noexcept specification:  

noexcept

  

Example

Run this code

#include <iostream>
#include <string>
#include <tuple>
 
int main()
{
    auto t = std::make_tuple(1, "Foo", 3.14);
    // index-based access
    std::cout << "(" << std::get<0>(t) << ", " << std::get<1>(t)
              << ", " << std::get<2>(t) << ")\n";
    // type-based access
    std::cout << "(" << std::get<int>(t) << ", " << std::get<const char*>(t)
              << ", " << std::get<double>(t) << ")\n";
}

Output:

(1, Foo, 3.14)
(1, Foo, 3.14)

See also

std::get(std::array)	accesses an element of an array (function template)
std::get(std::pair) (C++11)	accesses an element of a pair (function template)