std::array<T,N>::empty

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:

#include <array>
#include <iostream>
 
int main()
{
    std::array<int, 4> numbers {3, 1, 4, 1};
    std::array<int, 0> no_numbers;
 
    std::cout << "numbers.empty(): " << numbers.empty() << '\n';
    std::cout << "no_numbers.empty(): " << no_numbers.empty() << '\n';
}

Output:

numbers.empty(): 0
no_numbers.empty(): 1

See also

returns the number of elements
(public member function)

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