STL Queue in C++

The queue container in C++ provides a simple and efficient way to implement a queue data structure. It follows the First-In-First-Out (FIFO) principle, where elements are inserted at the back and removed from the front. The queue container is part of the C++ Standard Template Library (STL) and is included in the <queu> header.
Step 1: Include the necessary header file

#include<queue>

Step 2: Declare a queue object

std::queue<T> myQueue;

Replace T with the type of elements you want to store in the queue.
Step 3: Insert elements into the queue

myQueue.push(element);

This adds the element to the back of the queue.
Step 4: Access the front element

T frontElement = myQueue.front();

This retrieves the front element of the queue without removing it.
Step 5: Remove the front element

myQueue.pop();

This removes the front element from the queue.
Step 6: Check if the queue is empty

bool isEmpty = myQueue.empty();

This returns true if the queue is empty; otherwise, it returns false.
Step 7: Get the size of the queue

size_t queueSize = myQueue.size();

This returns the number of elements currently stored in the queue.
Here's an example that demonstrates the usage of queue:

#include<iostream>
#include<queue>
int main() {
  std::queue<int> myQueue;
  // Insert elements into the queue
  myQueue.push(10);
  myQueue.push(20);
  myQueue.push(30);
  // Access the front element
  int frontElement = myQueue.front();
  std::cout << "Front element: " << frontElement << std::endl;
  // Remove the front element
  myQueue.pop();
  // Check if the queue is empty
  bool isEmpty = myQueue.empty();
  std::cout << "Is queue empty? " << (isEmpty ? "Yes" : "No") << std::endl;
  // Get the size of the queue
  size_t queueSize = myQueue.size();
  std::cout << "Queue size: " << queueSize << std::endl;
  return 0;
}

Output:

Front element: 10
Is queue empty? No
Queue size: 2