Stack Using Link List Code

// Stack Using Link List

#include<stdio.h>
#include<process.h>
#include<malloc.h>
struct link{
 int data;
 struct link *next;
};
typedef struct link node;
node* top=NULL;
main()
{
 void push(int);int pop();void display();
 int data,ch,x;
 printf("Menu\n1.Push\n2.POP\n3.Display\n4.Exit\n");
 do{
  printf("\nEnter your Choice\n");
  scanf("%d",&ch);
  switch(ch)
  {
   case 1:
    printf("Enter data\n");
    scanf("%d",&data);
    push(data);
    break;
    case 2:
     x=pop();
     printf("Deleted data is = %d\n",x);
     break;
     case 3:
      display();
      break;
      case 4:
       exit(1);
       default:
        printf("Wrong choice\n");
  }
  
 }while(ch!=4);
}
void push(int x)
{
 node* nnode;
 nnode=(node*)malloc(sizeof(node));
 nnode->data=x;
 nnode->next=top;
 top=nnode;
}
int pop()
{
 int k;
 node* t;//we took t node to make memory free of node t
 t=top;
 if(top==NULL)
 printf("\nThere is no data\n");
 else{
  k=top->data;
  top=top->next;
  return(k);
  free(t);
 }
}
void display()
{
 node* i;
 if(top==NULL)
 printf("Nothing to Display\n");
 else{
  i=top;
  for(i=top;i!=NULL;i=i->next)
  {
   printf("%d ",i->data);
  }
 }
}