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std::get(std::tuple)

	(1)
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type& get( tuple<Types...>& t );		(since C++11) (until C++14)
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >& get( tuple<Types...>& t );		(since C++14)
		(2)
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type&& get( tuple<Types...>&& t );			(since C++11) (until C++14)
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >&& get( tuple<Types...>&& t );			(since C++14)
			(3)
template< std::size_t I, class... Types > typename std::tuple_element<I, tuple<Types...> >::type const& get( const tuple<Types...>& t );				(since C++11) (until C++14)
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >const& get( const tuple<Types...>& t );				(since C++14)
template< std::size_t I, class... Types > constexpr std::tuple_element_t<I, tuple<Types...> >const&& get( const tuple<Types...>&& t );				(4)	(since C++17)
template< class T, class... Types > constexpr T& get(tuple<Types...>& t);				(5)	(since C++14)
template< class T, class... Types > constexpr T&& get(tuple<Types...>&& t);				(6)	(since C++14)
template< class T, class... Types > constexpr const T& get(const tuple<Types...>& t);				(7)	(since C++14)
template< class T, class... Types > constexpr const T&& get(const tuple<Types...>&& t);				(8)	(since C++17)

1-4) Extracts the Ith element from the tuple. I is an integer value in [0, sizeof...(Types)).

5-8) 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

tuple whose contents to extract

Return value

A reference to the selected element of t.

Exceptions

noexcept specification:

noexcept

Example

#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)

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)
std::get(std::variant) (C++17)	reads the value of the variant given the index or the type (if the type is unique), throws on error (function template)

std::get(std::tuple)

Parameters

Return value

Exceptions

Example

See also