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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: /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;
+}