| 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 | } |