Add a new node at the end of linked list using recursion

C: 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 ;
    }
}