Difference between stack and queue?

Akshay Amin

Jul 21

699

Key difference between Stack and Queue is how elements are added and removed.

Stack

Order: Last In, First Out (LIFO)
Operations:
1. Push: Add an element to the top
2. Pop: Remove the top element
Use Case: Undo functionality in software, where the last action is undone first.
Example:
1. Stack (Top → Bottom):
2. [5]
3. [3]
4. [1] ← First inserted
5. Pop removes 5, the last inserted.

Queue

Order: First In, First Out (FIFO)
Operations:
1. Enqueue: Add an element to the end
2. Dequeue: Remove the front element
Use Case: Print queue, where the first document sent is printed first.
Example:
1. Queue (Front → Rear):
2. [1] ← First inserted
3. [3]
4. [5]
5. Dequeue removes 1, the first inserted.

Pankajkumar Patel

STACK A stack is a linear data structure that follows the LIFO (Last In, First Out) principle. This means the element inserted last will be removed first. Key Features: Elements are added and removed from the same end (called TOP).Works like a stack of plates — the last plate kept is the first to be taken out.Operations:Push: Insert an element into the stack.Pop: Remove the top element from the stack.Peek/Top: View the top element without removing it.Example: Imagine a pile of books 📚.You keep placing books on top (push).To take one, you remove the topmost book first (pop).Applications of Stack:Undo/Redo functionality in editorsBrowser history (back and forward buttons)Expression evaluation in programmingRecursive function callsQUEUE Definition: A queue is a linear data structure that follows the FIFO (First In, First Out) principle. This means the element inserted first will be removed first.Key Features:Elements are added at the rear (enqueue) and removed from the front (dequeue).Works like a bus queue — the first person in line gets in the bus first.Operations:Enqueue: Insert an element at the rear.Dequeue: Remove an element from the front.Peek/Front: View the front element without removing it.Example: A ticket counterThe person who comes first gets the ticket first.

Gaurav Kumar

Aug 26