NAME¶

std::array::empty - std::array::empty

Synopsis¶

constexpr bool empty() const noexcept; (since C++11)
(until C++20)
[[nodiscard]] constexpr bool empty() const noexcept; (since C++20)

Checks if the container has no elements, i.e. whether begin() == end().

Parameters¶

(none)

Return value¶

true if the container is empty, false otherwise

Complexity¶

Constant.

Example¶

The following code uses empty to check if a std::array contains any elements:

// Run this code

#include <array>
#include <iostream>

int main()
{
std::array<int, 4> numbers {3, 1, 4, 1};
std::array<int, 0> no_numbers;

std::cout << std::boolalpha;
std::cout << "numbers.empty(): " << numbers.empty() << '\n';
std::cout << "no_numbers.empty(): " << no_numbers.empty() << '\n';
}

Output:¶

numbers.empty(): false
no_numbers.empty(): true

See also¶

size returns the number of elements
(C++11) (public member function)
empty checks whether the container is empty
(C++17) (function template)