std::get(std::tuple)

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Utilities library

Type support (basic types, RTTI, type traits)

Dynamic memory management

Error handling

Program utilities

Variadic functions

Date and time

Function objects

initializer_list (C++11)

bitset

hash (C++11)

Relational operators

rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>=

Pairs and tuples

pair

tuple (C++11)

piecewise_construct_t (C++11)

piecewise_construct (C++11)

integer_sequence (C++14)

Swap, forward and move

swap

exchange (C++14)

forward (C++11)

move (C++11)

move_if_noexcept (C++11)

declval (C++11)

 

std::tuple

Member functions

tuple::tuple

tuple::operator=

tuple::swap

Non-member functions

make_tuple

tie

forward_as_tuple

tuple_cat

operator==operator!=operator<operator<=operator>operator>=

std::swap

get

Helper classes

tuple_size

tuple_element

uses_allocator

ignore

 

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 std::tuple_element_t<I, tuple<Types...> >&     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 std::tuple_element_t<I, tuple<Types...> >&&     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 std::tuple_element_t<I, tuple<Types...> >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)