Stack – Data Structure

Outline:

• Introduction
• Implementation (static and dynamic)
• Application

Stack – Introduction

• Stack is a linear data structure.
• Stack follows the order as:
  • LIFO(Last In First Out) or
  • FILO(First In Last Out).
• Operations performed on the stack:
  • Push: Adds an item in the stack. If the stack is full, then it is said to be an Overflow condition.
  • Pop: Removes an item from the stack. The items are popped in the LIFO order.
    • If the stack is empty, then it is said to be an Underflow condition.
• Peek or Top: Returns top element of stack.
• isEmpty: Returns true if stack is empty, else false.

Stack -Implementation:

• Stack can be implemented in two ways:
  • Using array
  • Using linked list

Stack – Implementation – using Array:

• PUSH Operation Algorithm

                begin procedure push: stack, data
                   if stack is full
                      return null
                   endif
                   top = top + 1
                   stack[top] = data
                end procedure

 

• POP Operation Algorithm:

               begin procedure pop: stack 
	           if stack is empty 
		       return null 
	           endif 
	           data = stack[top] 
	           top = top - 1 
	           return data 
                end procedure