1 extern int printf (const char *,...);
2 
3 struct s { struct s *n; } *p;
4 struct s ss;
5 #define MAX     10
6 struct s sss[MAX];
7 int count = 0;
8 
9 void sub( struct s *p, struct s **pp );
10 int look( struct s *p, struct s **pp );
11 
12 main()
13 {
14     struct s *pp;
15     struct s *next;
16     int i;
17 
18     p = &ss;
19     next = p;
20     for ( i = 0; i < MAX; i++ ) {
21         next->n = &sss[i];
22         next = next->n;
23     }
24     next->n = 0;
25 
26     sub( p, &pp );
27     if (count != MAX+2)
28       abort ();
29 
30     exit( 0 );
31 }
32 
33 void sub( struct s *p, struct s **pp )
34 {
35    for ( ; look( p, pp ); ) {
36         if ( p )
37             p = p->n;
38         else
39             break;
40    }
41 }
42 
43 int look( struct s *p, struct s **pp )
44 {
45     for ( ; p; p = p->n )
46         ;
47     *pp = p;
48     count++;
49     return( 1 );
50 }
51