strstr.c revision 130561 
1/* Simple implementation of strstr for systems without it.
2   This function is in the public domain.  */
3
4/*
5
6@deftypefn Supplemental char* strstr (const char *@var{string}, const char *@var{sub})
7
8This function searches for the substring @var{sub} in the string
9@var{string}, not including the terminating null characters.  A pointer
10to the first occurrence of @var{sub} is returned, or @code{NULL} if the
11substring is absent.  If @var{sub} points to a string with zero
12length, the function returns @var{string}.
13
14@end deftypefn
15
16
17*/
18
19
20/* FIXME:  The above description is ANSI compiliant.  This routine has not
21   been validated to comply with it.  -fnf */
22
23char *
24strstr (s1, s2)
25  char *s1, *s2;
26{
27  register char *p = s1;
28  extern char *strchr ();
29  extern int strncmp ();
30#if __GNUC__ >= 2
31  extern __SIZE_TYPE__ strlen (const char *);
32#endif
33  register int len = strlen (s2);
34
35  for (; (p = strchr (p, *s2)) != 0; p++)
36    {
37      if (strncmp (p, s2, len) == 0)
38	{
39	  return (p);
40	}
41    }
42  return (0);
43}
44