<array> functions

The <array> header includes three non-member functions, get, swap, and to_array that operate on array objects.

get

Returns a reference to the specified element of the array.

template <std::size_t Index, class Type, std::size_t Size>
constexpr Type& get(std::array<Type, Size>& arr) noexcept;

template <std::size_t Index, class Type, std::size_t Size>
constexpr const Type& get(const std::array<Type, Size>& arr) noexcept;

template <std::size_t Index, class Type, std::size_t Size>
constexpr Type&& get(std::array<Type, Size>&& arr) noexcept;

template <std::size_t Index, class Type, std::size_t Size>
constexpr const Type&& get(const std::array<Type, Size>&& arr) noexcept;

Template parameters

Index
The element offset.

Type
The type of an element.

Size
The number of elements in the array.

Parameters

arr
The array to select from.

Example

#include <array>
#include <iostream>

using namespace std;

typedef array<int, 4> MyArray;

int main()
{
    MyArray c0 { 0, 1, 2, 3 };

    // display contents " 0 1 2 3"
    for (const auto& e : c0)
    {
        cout << " " << e;
    }
    cout << endl;

    // display odd elements " 1 3"
    cout << " " << get<1>(c0);
    cout << " " << get<3>(c0) << endl;
}

0 1 2 3
1 3

swap

A non-member template specialization of std::swap that swaps two array objects.

template <class Type, std::size_t Size>
void swap(std::array<Type, Size>& left, std::array<Type, Size>& right);

Template parameters

Type
The type of an element.

Size
The size of the array.

Parameters

left
The first array to swap.

right
The second array to swap.

Remarks

The template function executes left.swap(right).

Example

// std__array__swap.cpp
// compile with: /EHsc
#include <array>
#include <iostream>

typedef std::array<int, 4> Myarray;
int main()
{
    Myarray c0 = { 0, 1, 2, 3 };

    // display contents " 0 1 2 3"
    for (Myarray::const_iterator it = c0.begin();
        it != c0.end(); ++it)
        std::cout << " " << *it;
    std::cout << std::endl;

    Myarray c1 = { 4, 5, 6, 7 };
    c0.swap(c1);

    // display swapped contents " 4 5 6 7"
    for (Myarray::const_iterator it = c0.begin();
        it != c0.end(); ++it)
        std::cout << " " << *it;
    std::cout << std::endl;

    swap(c0, c1);

    // display swapped contents " 0 1 2 3"
    for (Myarray::const_iterator it = c0.begin();
        it != c0.end(); ++it)
        std::cout << " " << *it;
    std::cout << std::endl;

    return (0);
}

0 1 2 3
4 5 6 7
0 1 2 3

to_array

Converts a built-in array to a std::array object.

// C++20
template <class Type, std::size_t Size>
constexpr std::array<std::remove_cv_t<Type>, Size> to_array(Type (&arr)[Size]);

// C++20
template <class Type, std::size_t Size>
constexpr std::array<std::remove_cv_t<Type>, Size> to_array(Type (&&arr)[Size]);

Template parameters

Type
The type of an element.

Size
The size of the input array.

Parameters

arr
The input array used for conversion.

Example

// std_to_array.cpp
// Requires /std:c++20 or later

#include <array>
#include <iostream>

int main()
{
    int arr1[]{ 1, 2, 3 };
    std::array<int, 3> arr2 = std::to_array(arr1);

    std::cout << "std::to_array(arr1):\n";
    for (const auto& i : arr2)
    {
        std::cout << i << " ";
    }
    std::cout << std::endl;

    // The size is 7 as it includes the null terminator
    std::array<char, 7> arr3 = std::to_array("string");

    std::cout << "\nstd::to_array(\"string\"):\n";
    for (const auto& i : arr3)
    {
        std::cout << i << " ";
    }
    std::cout << std::endl;
}

std::to_array(arr1):
1 2 3 

std::to_array("string"):
s t r i n g 

See also

<array>