Building a Stack Using Lists - Python Programming Exercise

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

    def push(self, item):
        """Adds an item to the top of the stack."""
        self.stack.append(item)
        print(f"Item '{item}' pushed onto the stack.")

    def pop(self):
        """Removes and returns the top item from the stack."""
        if self.is_empty():
            print("Error: The stack is empty. Cannot perform pop.")
        else:
            item = self.stack.pop()
            print(f"Item '{item}' popped from the stack.")
            return item

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

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


def main():
    """Main function to interact with the stack."""
    s = Stack()

    while True:
        print("\nOptions:")
        print("1. Push (Add item to the stack)")
        print("2. Pop (Remove item from the stack)")
        print("3. Display stack contents")
        print("4. Exit")
        
        choice = input("Choose an option (1/2/3/4): ")

        if choice == "1":
            item = input("Enter the item to push onto the stack: ")
            s.push(item)
        elif choice == "2":
            s.pop()
        elif choice == "3":
            s.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. Push (Add item to the stack)
2. Pop (Remove item from the stack)
3. Display stack contents
4. Exit
Choose an option (1/2/3/4): 1
Enter the item to push onto the stack: Book
Item 'Book' pushed onto the stack.

Options:
1. Push (Add item to the stack)
2. Pop (Remove item from the stack)
3. Display stack contents
4. Exit
Choose an option (1/2/3/4): 3
Current contents of the stack: ['Book']

Options:
1. Push (Add item to the stack)
2. Pop (Remove item from the stack)
3. Display stack contents
4. Exit
Choose an option (1/2/3/4): 2
Item 'Book' popped from the stack.

Options:
1. Push (Add item to the stack)
2. Pop (Remove item from the stack)
3. Display stack contents
4. Exit
Choose an option (1/2/3/4): 3
The stack is empty.

Options:
1. Push (Add item to the stack)
2. Pop (Remove item from the stack)
3. Display stack contents
4. Exit
Choose an option (1/2/3/4): 4
Exiting the program.