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std::get(std::array)

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

Extracts the Ith element from the array using tuple-like interface.

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

Contents

[edit] Parameters

a - array whose contents to extract

[edit] Return value

A reference to the Ith element of a.

[edit] Complexity

Constant.

[edit] Example

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

Output:

(1,2,3)

[edit] 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

[edit] See also

Structured binding (C++17) binds the specified names to sub-objects or tuple elements of the initializer[edit]
access specified element
(public member function) [edit]
access specified element with bounds checking
(public member function) [edit]
tuple accesses specified element
(function template) [edit]
accesses an element of a pair
(function template) [edit]
reads the value of the variant given the index or the type (if the type is unique), throws on error
(function template) [edit]
obtains iterator or sentinel from a std::ranges::subrange
(function template) [edit]