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 8 This function searches for the substring @var{sub} in the string 9 @var{string}, not including the terminating null characters. A pointer 10 to the first occurrence of @var{sub} is returned, or @code{NULL} if the 11 substring is absent. If @var{sub} points to a string with zero 12 length, 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 23 #include <stddef.h> 24 25 extern char *strchr (const char *, int); 26 extern int strncmp (const void *, const void *, size_t); 27 extern size_t strlen (const char *); 28 29 char * 30 strstr (const char *s1, const char *s2) 31 { 32 const char *p = s1; 33 const size_t len = strlen (s2); 34 35 for (; (p = strchr (p, *s2)) != 0; p++) 36 { 37 if (strncmp (p, s2, len) == 0) 38 return (char *)p; 39 } 40 return (0); 41 } 42
