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/*
* 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: /home/cvs/ruby/missing/strstr.c,v 1.1.1.2 1999/01/20 04:59:37 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;
}
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