NAME¶

std::queue::empty - std::queue::empty

Synopsis¶

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

Checks if the underlying container has no elements. Equivalent to return c.empty();.

Parameters¶

(none)

Return value¶

true if the underlying container is empty, false otherwise.

Complexity¶

Constant.

Example¶

// Run this code

#include <algorithm>
#include <iostream>
#include <queue>

int main()
{
std::cout << std::boolalpha;

std::queue<int> queue;

std::cout << "Initially, queue.empty(): " << queue.empty() << '\n';

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

Output:¶

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

See also¶

size returns the number of elements
(public member function)
empty checks whether the container is empty
(C++17) (function template)