Can you show me some examples of stack implementation in Python?

Can you show me some examples of stack implementation in Python?

Sure! A stack can be implemented using a list in Python. Here's a simple example:

class Stack:
    def __init__(self):
        self.stack = []

    def push(self, item):
        self.stack.append(item)

    def pop(self):
        if not self.is_empty():
            return self.stack.pop()
        return 'Stack is empty!'

    def is_empty(self):
        return len(self.stack) == 0

    def peek(self):
        if not self.is_empty():
            return self.stack[-1]
        return 'Stack is empty!'

    def size(self):
        return len(self.stack)

# Example usage:
my_stack = Stack()
my_stack.push(1)
my_stack.push(2)
print(my_stack.pop())  # Output: 2

What are the main operations of a stack?

The main operations of a stack are:

1. Push: Add an item to the top of the stack.
2. Pop: Remove and return the item from the top of the stack.
3. Peek: Return the item at the top of the stack without removing it.
4. is_empty: Check if the stack is empty.
5. size: Return the number of items in the stack.

Can you explain how to use the stack for reversing a string?

Absolutely! You can use a stack to reverse a string by pushing each character onto the stack and then popping them off. Here's an example:

def reverse_string(s):
    stack = Stack()
    for char in s:
        stack.push(char)
    reversed_str = ''
    while not stack.is_empty():
        reversed_str += stack.pop()
    return reversed_str

# Example usage:
print(reverse_string('hello'))  # Output: 'olleh'