std::vector<T,Allocator>::empty (3) - Linux Manuals

std::vector<T,Allocator>::empty: std::vector<T,Allocator>::empty

NAME

std::vector<T,Allocator>::empty - std::vector<T,Allocator>::empty

Synopsis

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

// Run this code

  #include <vector>
  #include <iostream>

  int main()
  {
      std::cout << std::boolalpha;
      std::vector<int> numbers;
      std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n';

      numbers.push_back(42);
      std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n';
  }

Output:

  Initially, numbers.empty(): true
  After adding elements, numbers.empty(): false