What is the difference between push and pop in data structure?

Understanding Push and Pop

Push and pop are fundamental operations in stack data structures. They are used to add and remove elements from the stack, respectively.

Pushing Elements

• Push adds an element to the top of the stack. Imagine a stack of plates – when you add a new plate, it goes on top of the existing ones.
• Example:
  • If you have a stack with elements [1, 2, 3] and you push the element 4, the stack becomes [1, 2, 3, 4].

Popping Elements

• Pop removes the element at the top of the stack. Again, using the plate analogy, when you pop a plate, you remove the topmost one.
• Example:
  • If you have a stack with elements [1, 2, 3, 4] and you pop an element, the stack becomes [1, 2, 3].

Key Differences

• Push adds to the stack, while pop removes from the stack.
• Push operates on the top of the stack, while pop also operates on the top.
• Push increases the size of the stack, while pop decreases the size.

Practical Applications

Push and pop are crucial in various programming scenarios, including:

• Function call stacks: When a function is called, its parameters and local variables are pushed onto the stack. When the function completes, its elements are popped off.
• Undo/redo functionality: Stacks can be used to store the history of actions, allowing users to undo or redo their changes.
• Expression evaluation: Stacks are used to parse and evaluate mathematical expressions by storing operators and operands.