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authorrjohnson <rjohnson>1998-03-26 14:45:59 (GMT)
committerrjohnson <rjohnson>1998-03-26 14:45:59 (GMT)
commit2b5738da524e944cda39e24c0a87b745a43bd8c3 (patch)
tree6e8c9473978f6dab66c601e911721a7bd9d70b1b /compat/strstr.c
parentc6a259aeeca4814a97cf6694814c63e74e4e18fa (diff)
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+/*
+ * strstr.c --
+ *
+ * Source code for the "strstr" library routine.
+ *
+ * Copyright (c) 1988-1993 The Regents of the University of California.
+ * Copyright (c) 1994 Sun Microsystems, Inc.
+ *
+ * See the file "license.terms" for information on usage and redistribution
+ * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+ *
+ * SCCS: @(#) strstr.c 1.4 96/02/15 12:08:22
+ */
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * 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;
+}