Implementing a Queue Using List - Python Programming Exercise

class Queue:
    """Class to implement a queue using a list."""
    
    def __init__(self):
        """Initializes the queue as an empty list."""
        self.queue = []

    def enqueue(self, item):
        """Adds an item to the end of the queue."""
        self.queue.append(item)
        print(f"Item '{item}' added to the queue.")

    def dequeue(self):
        """Removes and returns the first item from the queue."""
        if self.is_empty():
            print("Error: The queue is empty. Cannot perform dequeue.")
        else:
            item = self.queue.pop(0)
            print(f"Item '{item}' removed from the queue.")
            return item

    def is_empty(self):
        """Checks if the queue is empty."""
        return len(self.queue) == 0

    def display(self):
        """Displays the current state of the queue."""
        if self.is_empty():
            print("The queue is empty.")
        else:
            print("Current state of the queue:", self.queue)


def main():
    """Main function to interact with the queue."""
    q = Queue()

    while True:
        print("\nOptions:")
        print("1. Enqueue (Add item to the queue)")
        print("2. Dequeue (Remove item from the queue)")
        print("3. Display queue state")
        print("4. Exit")
        
        choice = input("Choose an option (1/2/3/4): ")

        if choice == "1":
            item = input("Enter the item to add to the queue: ")
            q.enqueue(item)
        elif choice == "2":
            q.dequeue()
        elif choice == "3":
            q.display()
        elif choice == "4":
            print("Exiting the program.")
            break
        else:
            print("Invalid option. Please choose a valid option.")


# Run the program
if __name__ == "__main__":
    main()

 Output

Options:
1. Enqueue (Add item to the queue)
2. Dequeue (Remove item from the queue)
3. Display queue state
4. Exit
Choose an option (1/2/3/4): 1
Enter the item to add to the queue: Apple
Item 'Apple' added to the queue.

Options:
1. Enqueue (Add item to the queue)
2. Dequeue (Remove item from the queue)
3. Display queue state
4. Exit
Choose an option (1/2/3/4): 3
Current state of the queue: ['Apple']

Options:
1. Enqueue (Add item to the queue)
2. Dequeue (Remove item from the queue)
3. Display queue state
4. Exit
Choose an option (1/2/3/4): 2
Item 'Apple' removed from the queue.

Options:
1. Enqueue (Add item to the queue)
2. Dequeue (Remove item from the queue)
3. Display queue state
4. Exit
Choose an option (1/2/3/4): 3
The queue is empty.

Options:
1. Enqueue (Add item to the queue)
2. Dequeue (Remove item from the queue)
3. Display queue state
4. Exit
Choose an option (1/2/3/4): 4
Exiting the program.