std::vector<T,Allocator>::empty - cppreference.com (original) (raw)

| bool empty() const; | | (noexcept since C++11) (constexpr since C++20) | | ------------------- | | ---------------------------------------------- |

Checks if the container has no elements.

[edit] Return value

true if the container is empty, false otherwise.

[edit] Complexity

Constant.

[edit] Example

#include #include   int main() { std::cout << std::boolalpha;   std::vector 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

[edit] See also

| | returns the number of elements (public member function) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | | checks whether the container is empty (function template) [edit] |