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Implement Queue

Description​

The code implements queue operations using a list in Python, allowing users to add elements, remove elements, and display the current contents of the queue interactively.

Code​

expt10a.py
# Queue
queue = []

def enqueue():
    element = input("Enter the element: ")
    queue.append(element)
    print("Element is added to queue")
    print(queue)

def dequeue():
    if not queue:
        print("Queue is empty")
    else:
        e = queue.pop(0)
        print("Element removed ", e)
        print(queue)

def display():
    print(queue)

while True:
    print("Select the operation: 1. Add  2. Remove  3. Show  4. Quit")
    choice = int(input())
    if choice == 1:
        enqueue()
    elif choice == 2:
        dequeue()
    elif choice == 3:
        display()
    elif choice == 4:
        print("Quit")
        break
    else:
        print("Enter the correct operation")

Explanation of above code​

  • The provided code implements a queue data structure using a list in Python. It offers the following operations:
  • enqueue(): This operation adds an element to the end of the queue. It prompts the user to enter an element, appends it to the queue list, and displays a message along with the updated queue.
  • dequeue(): This operation removes an element from the front of the queue. If the queue is empty, it displays a message. Otherwise, it removes the element at index 0 from the queue list using pop(0), displays the removed element, and shows the updated queue.
  • display(): This operation displays the current contents of the queue by printing the queue list.

Code Explanation​

  • The code initializes an empty list called queue to store the elements.
  • The enqueue() function prompts the user to enter an element, appends it to the queue list, and displays a message along with the updated queue.
  • The dequeue() function checks if the queue list is empty. If it is, it prints a message indicating that the queue is empty. Otherwise, it removes the element at index 0 using pop(0), stores it in the variable e, prints the removed element, and shows the updated queue.
  • The display() function simply prints the queue list to display the current contents.
  • The program enters an infinite loop using while True. It displays a menu to the user with the available operations: Add, Remove, Show, and Quit. It prompts the user to enter a choice (1-4). Based on the user's choice, it calls the corresponding operation function (enqueue(), dequeue(), display()), or exits the loop if the choice is 4 (Quit). If the choice is not valid, it displays a message indicating that the user should enter the correct operation.
  • This code allows users to interactively perform queue operations and see the resulting changes in the queue.

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Reference​