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)

Filesystem library (C++17)

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>=

optional, any and variant (C++17)

optional

any

variant

in_placein_place_typein_place_indexin_place_tin_place_type_tin_place_index_t

Pairs and tuples

pair

tuple (C++11)

apply (C++17)

make_from_tuple (C++17)

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)

Elementary string conversions

to_chars (C++17)

from_chars (C++17)

chars_format (C++17)

Type operations

declval (C++11)

as_const (C++17)

 

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

 

	(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

t

-

tuple whose contents to extract

Return value

A 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)
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)