A STACK is a simple Data Structure, It can be implemented as an array or as Linked List, Stack has only One End that is TOP, Item can be pushed (add) and popped (remove) by only this End (TOP Pointer). Array follows LIFO (Last In First Out) property, it means Item that is inserted Last will be popped first.
#include <stdio.h>
#include <stdlib.h>
#define MAX 10
int STACK[MAX],TOP;
/* display stack element*/
void display(int []);
/* push (insert) item into stack*/
void PUSH(int [],int);
/* pop (remove) item from stack*/
void POP (int []);
void main()
{
int ITEM=0;
int choice=0;
TOP=-1;
while(1)
{
/*clrscr();*/
printf("Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..:");
scanf("%d",&choice);
switch(choice)
{
case 1:
display(STACK);
break;
case 2:
printf("Enter Item to be insert :");
scanf("%d",&ITEM);
PUSH(STACK,ITEM);
break;
case 3:
POP(STACK);
break;
case 4:
exit(0);
default:
printf("\nInvalid choice.");
break;
}
getch();
}// end of while(1)
}
/* function : display(),
to display stack elements.
*/
void display(int stack[])
{
int i=0;
if(TOP==-1)
{
printf("Stack is Empty .\n");
return;
}
printf("%d <-- TOP ",stack[TOP]);
for(i=TOP-1;i >=0;i--)
{
printf("\n%d",stack[i]);
}
printf("\n\n");
}
/* function : PUSH(),
to push an item into stack.
*/
void PUSH(int stack[],int item)
{
if(TOP==MAX-1)
{
printf("\nSTACK is FULL CAN't ADD ITEM\n");
return;
}
TOP++;
stack[TOP]=item;
}
/* function : POP(),
to pop an item from stack.
*/
void POP(int stack[])
{
int deletedItem;
if(TOP==-1)
{
printf("STACK is EMPTY.\n");
return;
}
deletedItem=stack[TOP];
TOP--;
printf("%d deleted successfully\n",deletedItem);
return;
}
