std::array<T,N>::empty (3) - Linux Manuals

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

NAME

std::array<T,N>::empty - std::array<T,N>::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 << "numbers.empty(): " << numbers.empty() << '\n';
      std::cout << "no_numbers.empty(): " << no_numbers.empty() << '\n';
  }

Output:

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