Program to add a new node at the end of linked list using recursion

#include <"stdio.h">
#include <"conio.h">
#include <"alloc.h">

struct node
{
int data ;
struct node *link ;
} ;

void addatend ( struct node **, int ) ;
void display ( struct node * ) ;

void main( )
{
struct node *p ;

p = NULL ;

addatend ( &p, 1 ) ;
addatend ( &p, 2 ) ;
addatend ( &p, 3 ) ;
addatend ( &p, 4 ) ;
addatend ( &p, 5 ) ;
addatend ( &p, 6 ) ;
addatend ( &p, 10 ) ;

clrscr( ) ;
display ( p ) ;
}

/* adds a new node at the end of the linked list */
void addatend ( struct node **s, int num )
{
if ( *s == NULL )
{
*s = malloc ( sizeof ( struct node ) ) ;
( *s ) -> data = num ;
( *s ) -> link = NULL ;
}
else
addatend ( &( ( *s ) -> link ), num ) ;
}

/* displays the contents of the linked list */
void display ( struct node *q )
{
printf ( "\n" ) ;

/* traverse the entire linked list */
while ( q != NULL )
{
printf ( "%d ", q -> data ) ;
q = q -> link ;
}
}