stack using linked list

#include<stdio.h>

#include<conio.h>

#include<malloc.h>

struct node

{

 int info;

 struct node*next;

};

struct node *top=NULL;

void push(int item)

{

 struct node *p;

 p=(struct node*)malloc(sizeof(struct node));

 p->info=item;

 p->next=top;

 top=p;

 printf("\ninserted element %d",p->info);

}

void pop()

{

 struct node *p;

 p=top;

 if(p==NULL)

 printf("\nempty");

 else

 {

  top=top->next;

  printf("\nelement deleted %d",p->info);

  free(p);

 }

}

void display()

{

 struct node *p;

 p=top;

 if(p==NULL)

 printf("\nempty");

 else

 {

  while(p!=NULL)

  {

   printf("\n%d",p->info);

   p=p->next;

  }

 }

}

void main()

{

 int item,ch;

 clrscr();

 printf("\nMENIU OPTIONS\n1.push\n2.pop\n3.display\n4.exit");

 do

 {

  printf("\nenter your choice");

  scanf("%d",&ch);

  switch(ch)

  {

   case 1:printf("\nenter the element to push");

                  scanf("%d",&item);

                  push(item);

                  break;

   case 2:pop();

                  break;

   case 3:display();

                  break;

   case 4:exit(0);

   default:printf("\ninvalid choice......");

  }

 }while(ch!=4);

 getch();

}