What are some examples of using std::queue in C++?

Can you give me some examples of using std::queue in C++?

Sure! The std::queue is a container adapter that provides a FIFO (first-in, first-out) data structure. Here's a simple example:

#include <iostream>
#include <queue>

int main() {
    std::queue<int> q;
    q.push(1);
    q.push(2);
    q.push(3);

    while (!q.empty()) {
        std::cout << q.front() << ' '; // Access the front element
        q.pop(); // Remove the front element
    }
    return 0;
}

This code will output: 1 2 3.

What happens if I try to access the front of an empty queue?

If you try to access the front of an empty queue using q.front(), it will lead to undefined behavior. It's important to check if the queue is empty using q.empty() before accessing the front element.

Can I store different data types in a std::queue?

No, std::queue is a template class, so it can only store elements of a single data type. If you need to store different types, you might consider using std::variant or a base class pointer.

How do I clear a std::queue?

You can clear a std::queue by repeatedly calling pop() until it is empty, or you can create a new queue and swap it with the old one to effectively clear it.