Stack using array c program

Aim: To implement stack using array in c program
program:

#include<stdio.h>

#define MAXSIZE 3

void push(int);

int pop();

void display();

int top=0;stack[MAXSIZE];

void main()

{

int item,n,ch;

clrscr();

while(1)

{

printf("1.push\n");

printf("2.pop\n");

printf("3.display\n");

printf("4.exit\n");

printf("enter your choice:");

scanf("%d",&ch);

switch(ch)

{

case 1:printf("enter the item you want to push:");

scanf("%d",&item);

push(item);

break;

case 2:item=pop();

printf("item deleted from stack is %d\n",item);

break;

case 3:display();

break;

default:exit(0);

}

}

}

void push(int item)

{

if(top==MAXSIZE)

printf("overflow");

else

{

top=top+1;

stack[top]=item;

}

}

int pop()

{

int item;

if(top==0)

{

printf("underflow");

exit(0);

}

else

{

item=stack[top];

top=top-1;

return item;

}

}

void display()

{

int i;

printf("elements of stack are \n");

for(i=1;i<=top;i++)

printf("%3d",stack[i]);

printf("\n");

}