diff options
Diffstat (limited to 'missing/strstr.c')
-rw-r--r-- | missing/strstr.c | 73 |
1 files changed, 73 insertions, 0 deletions
diff --git a/missing/strstr.c b/missing/strstr.c new file mode 100644 index 0000000000..ff28ebffd6 --- /dev/null +++ b/missing/strstr.c @@ -0,0 +1,73 @@ +/* + * strstr.c -- + * + * Source code for the "strstr" library routine. + * + * Copyright 1988-1991 Regents of the University of California + * Permission to use, copy, modify, and distribute this + * software and its documentation for any purpose and without + * fee is hereby granted, provided that the above copyright + * notice appears in all copies. The University of California + * makes no representations about the suitability of this + * software for any purpose. It is provided "as is" without + * express or implied warranty. + */ + +#ifndef lint +static char rcsid[] = "$Header: /work/cvsroot/ruby/missing/strstr.c,v 1.1 1994/06/27 15:49:21 matz Exp $ SPRITE (Berkeley)"; +#endif /* not lint */ + +/* + *---------------------------------------------------------------------- + * + * strstr -- + * + * Locate the first instance of a substring in a string. + * + * Results: + * If string contains substring, the return value is the + * location of the first matching instance of substring + * in string. If string doesn't contain substring, the + * return value is 0. Matching is done on an exact + * character-for-character basis with no wildcards or special + * characters. + * + * Side effects: + * None. + * + *---------------------------------------------------------------------- + */ + +char * +strstr(string, substring) + register char *string; /* String to search. */ + char *substring; /* Substring to try to find in string. */ +{ + register char *a, *b; + + /* First scan quickly through the two strings looking for a + * single-character match. When it's found, then compare the + * rest of the substring. + */ + + b = substring; + if (*b == 0) { + return string; + } + for ( ; *string != 0; string += 1) { + if (*string != *b) { + continue; + } + a = string; + while (1) { + if (*b == 0) { + return string; + } + if (*a++ != *b++) { + break; + } + } + b = substring; + } + return (char *) 0; +} |