strstr.c revision 130562
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