stack.py

# Stack implementation in python
# https://www.programiz.com/dsa/stack

# Creating a stack
def create_stack():
    stack = []
    return stack


# Creating an empty stack
def check_empty(stack):
    return len(stack) == 0


# Adding items into the stack
def push(stack, item):
    stack.append(item)
    print("pushed item: " + item)


# Removing an element from the stack
def pop(stack):
    if (check_empty(stack)):
        return "stack is empty"

    return stack.pop()


stack = create_stack()
push(stack, str(1))
push(stack, str(2))
push(stack, str(3))
push(stack, str(4))
print("popped item: " + pop(stack))
print("stack after popping an element: " + str(stack))



# class implementation for stack
class Stack(object):
	"""docstring for Stack"""
	def __init__(self):
		super(Stack, self).__init__()
		self.stack = []

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

	def pop(self):
		self.stack.pop()

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

	def peek(self):
		return self.stack[-1]

	def is_empty(self):
		if len(self.stack) < 1:
			return "Yes, it's empty"
		return "No, the size is {}".format(stack.size())

	def display(self):
		return self.stack

stack = Stack()
stack.push(1)
stack.push(2)
stack.push(3)
stack.push(4)
stack.push(2)
print(stack.peek())
print(stack.is_empty())
print(stack.display())
stack.pop()
print(stack.display())
stack.pop()
print(stack.display())
stack.pop()
stack.pop()
print(stack.display())
stack.pop()
print(stack.display())
print(stack.is_empty())