Write a program for addafter in linked list

#include<stdio.h>
#include<conio.h>
#include<alloc.h>
struct node
{
int data;
struct node *link;
};
void main()
{
struct node *p;
int c;
clrscr();
p=NULL;
addafter(p,7,0);
addafter(p,2,1);
addafter(p,5,99);
display(p);
getche();
}
int addafter(struct node *q,int n,int pos)
{
struct node *t,*r;
int i;
t=q;
for(i=0;i<pos;i++)
{
if(t->link==NULL)
break;
t=t->link;
}
r=(struct node*)malloc(sizeof(struct node));
r->data=n;
r->link=t->link;
t->link=r;
return 0;
}
int display(struct node *q)
{
while(q!=NULL)
{
printf("%d\t",q->data);
q=q->link;
}
return 0;
}