C Program to perform Stack Operations Using Pointer !

Write a C program using pointers to implement a stack with all the operations.

Program to implement stack with its operations using pointers

#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#define MAX 50
int size;
/* Defining the stack structure */
struct stack
{
    int AR[MAX];
    int top;
};
/* Initializing the stack(i.e., top=-1)   */
void init_stk(struct stack *st)
{
    st->top=-1;
}
/* Entering the elements into stack */
void push (struct stack *st,int num)
{
    if(st->top == size-1)
    {
    printf("\nStack overflow(i.e., stack full).");
    return;
    }
    st->top++;
    st->AR[st->top] = num;
}
//Deleting an element from the stack.
int pop(struct stack *st)
{
    int num;
    if(st->top == -1)
    {
    printf("\nStack underflow(i.e., stack empty).");
    return NULL;
    }
    num=st->AR[st->top];
    st->top--;
    return num;
}
void display(struct stack *st)
{
    int i;
    for(i=st->top;i>=0;i--)
        printf("\n%d",st->AR[i]);
}
void main()
{
    int ele,opt,val;
    struct stack ptr;
    clrscr();
    init_stk(&ptr);
    printf("\nEnter Stack Size :");
    scanf("%d",&size);
    while(1)
    {
        printf("\n\n\tSTACK PRIMITIVE OPERATIONS");
        printf("\n1.PUSH");
        printf("\n2.POP");
        printf("\n3.DISPLAY");
        printf("\n4.QUIT");
        printf("\n");
        printf("\nEnter your option : ");
        scanf("%d",&opt);
        switch(opt)
        {
            case 1:
                printf("\nEnter the element into stack:");
                scanf("%d",&val);
                push(&ptr,val);
                break;
            case 2:
                ele=pop(&ptr);
                printf("\nThe element popped from stack is : %d",ele);
                break;
            case 3:
                printf("\nThe current stack elements are:");
                display(&ptr);
                break;
            case 4:
                getch();
                exit(0);
            default:
                printf("\nEnter correct option!Try again.");
        }
    }
}

Output :