Stacks->Array Implementation->Pop operation

Algorithm:-
Step-1: If the Stack is empty then give the alert "Stack underflow" and quit; or else go to step-2
Step-2: a) Hold the value for the element pointed by the TOP
            b) Put a NULL value instead
            c) Decrement the TOP by 1

C implementation:-
static int stack[uplimit];
int top=-1;
..
..
main()
{
..
..
poped_val = pop();
..
poped_val = pop();
..
}

int push()
{
int del_val = 0;
if(top == -1) printf("Stack underflow"); /*step-1*/
  else
     {
      del_val = stack[top];  /*step-2*/
      stack[top] = NULL;
      top = top -1;
     } 
return(del_val);
}

Note:- Step-2:(b) signifies that the respective element has been deleted. In array implementation, I have taken TOP = -1 to signify the empty stack. This simplifies your implementation.

Related Operations:
Concept
Array Implementation - Push() and Pop()
Linked List Implementation - Push() and Pop()
Application of Stacks