std::unordered_set<Key,Hash,KeyEqual,Allocator>:: empty

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

#include <iostream>
#include <unordered_set>
 
int main()
{
    std::unordered_set<int> numbers;
    std::cout << std::boolalpha;
    std::cout << "Initially, numbers.empty(): " << numbers.empty() << '\n';
 
    numbers.insert(42);
    numbers.insert(19937);
    std::cout << "After adding elements, numbers.empty(): " << numbers.empty() << '\n';
}

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

See also