std::get(std::array)

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Iterator invalidation

Member function table

Non-member function table

 

std::array

Member types

Member functions

Element access

array::at

array::operator[]

array::front

array::back

array::data

Iterators

array::beginarray::cbegin

array::endarray::cend

array::rbeginarray::crbegin

array::rendarray::crend

Capacity

array::empty

array::size

array::max_size

Modifiers

array::fill

array::swap

Non-member functions

get

std::swap

to_array (C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Helper classes

tuple_size

tuple_element

Deduction guides(C++17)

 

Defined in header <array>
	(1)
template< std::size_t I, class T, std::size_t N > T& get( std::array<T,N>& a ) noexcept;			(since C++11) (until C++14)
template< std::size_t I, class T, std::size_t N > constexpr T& get( std::array<T,N>& a ) noexcept;			(since C++14)
		(2)
template< std::size_t I, class T, std::size_t N > T&& get( std::array<T,N>&& a ) noexcept;				(since C++11) (until C++14)
template< std::size_t I, class T, std::size_t N > constexpr T&& get( std::array<T,N>&& a ) noexcept;				(since C++14)
			(3)
template< std::size_t I, class T, std::size_t N > const T& get( const std::array<T,N>& a ) noexcept;					(since C++11) (until C++14)
template< std::size_t I, class T, std::size_t N > constexpr const T& get( const std::array<T,N>& a ) noexcept;					(since C++14)
				(4)
template< std::size_t I, class T, std::size_t N > const T&& get( const std::array<T,N>&& a ) noexcept;						(since C++11) (until C++14)
template< std::size_t I, class T, std::size_t N > constexpr const T&& get( const std::array<T,N>&& a ) noexcept;						(since C++14)

Extracts the I^th element from the array using tuple-like interface.

I must be an integer value in range [​0​, N). This is enforced at compile time as opposed to at() or operator[].

Parameters

a

-

array whose contents to extract

Return value

A reference to the I^th element of a.

Complexity

Constant.

Example

Run this code

#include <array>
#include <iostream>
 
int main()
{
    std::array<int, 3> arr;
 
    // set values:
    std::get<0>(arr) = 1;
    std::get<1>(arr) = 2;
    std::get<2>(arr) = 3;
 
    // get values:
    std::cout << '(' << std::get<0>(arr)
              << ',' << std::get<1>(arr)
              << ',' << std::get<2>(arr)
              << ")\n";
}

Output:

(1,2,3)

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 2485	C++11	there are no overloads for const array&&	the overloads are added

See also

Structured binding (C++17)	binds the specified names to sub-objects or tuple elements of the initializer
operator[] (C++11)	access specified element (public member function)
at (C++11)	access specified element with bounds checking (public member function)
std::get(std::tuple) (C++11)	tuple accesses specified element (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)
get(std::ranges::subrange) (C++20)	obtains iterator or sentinel from a std::ranges::subrange (function template)