Counting number of nodes in a Linked List through Recursion in C

#include <stdio.h>
#include <conio.h>
#include <malloc.h>
#include <windows.h>
/* structure containing a data part and link part */
struct node
{
 int data ;
 struct node *link ;
} ;
void append ( struct node **, int ) ;
int length ( struct node * ) ;
int main( )
{
 struct node *p ;
 p = NULL ;  /* empty linked list */
 append ( &p, 1 ) ;
 append ( &p, 2 ) ;
 append ( &p, 3 ) ;
 append ( &p, 4 ) ;
 append ( &p, 5 ) ;
 system ( "cls" ) ;
 printf ( "Length of linked list = %d\n", length ( p ) ) ;
 return 0 ;
}
/* adds a node at the end of a linked list */
void append ( struct node **q, int num )
{
 struct node *temp ;
 temp = *q ;
 if ( *q == NULL )  /* if the list is empty, create first node */
 {
  *q = ( struct node * ) malloc ( sizeof ( struct node ) ) ;
  temp = *q ;
 }
 else
 {
  /* go to last node */
  while ( temp -> link != NULL )
   temp = temp -> link ;
  /* add node at the end */
  temp -> link = ( struct node * ) malloc ( sizeof ( struct node ) ) ;
  temp = temp -> link ;
 }
 /* assign data to the last node */
 temp -> data = num ;
 temp -> link = NULL ;
}
/* counts the number of nodes in a linked list */
int length ( struct node *q )
{
 static int l ;
 /* if list is empty or if NULL is encountered */
 if ( q == NULL )
  return ( 0 ) ;
 else
 {
  /* go to next node */
  l = 1 + length ( q -> link ) ;
  return ( l ) ;
 }
}