std::queue::empty

Test whether container is empty

Returns whether the queue is empty: i.e. whether its size is zero.

This member function effectively calls member empty of the underlying container object.

Parameters

none

Return Value

true if the underlying container's size is 0, false otherwise.

Example

// queue::empty
#include <iostream>       // std::cout
#include <queue>          // std::queue

int main ()
{
  std::queue<int> myqueue;
  int sum (0);

  for (int i=1;i<=10;i++) myqueue.push(i);

  while (!myqueue.empty())
  {
     sum += myqueue.front();
     myqueue.pop();
  }

  std::cout << "total: " << sum << '\n';

  return 0;
}

The example initializes the content of the queue to a sequence of numbers (form 1 to 10). It then pops the elements one by one until it is empty and calculates their sum.

Output:

Complexity

Constant (calling empty on the underlying container).

Data races

The container is accessed.

Exception safety

Provides the same level of guarantees as the operation performed on the container (no-throw guarantee for standard container types).