sl@0: /* 
sl@0:  * strstr.c --
sl@0:  *
sl@0:  *	Source code for the "strstr" library routine.
sl@0:  *
sl@0:  * Copyright (c) 1988-1993 The Regents of the University of California.
sl@0:  * Copyright (c) 1994 Sun Microsystems, Inc.
sl@0:  *
sl@0:  * See the file "license.terms" for information on usage and redistribution
sl@0:  * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
sl@0:  *
sl@0:  * RCS: @(#) $Id: strstr.c,v 1.3.2.1 2005/04/12 18:28:56 kennykb Exp $
sl@0:  */
sl@0: 
sl@0: #include "tcl.h"
sl@0: #ifndef NULL
sl@0: #define NULL 0
sl@0: #endif
sl@0: 
sl@0: /*
sl@0:  *----------------------------------------------------------------------
sl@0:  *
sl@0:  * strstr --
sl@0:  *
sl@0:  *	Locate the first instance of a substring in a string.
sl@0:  *
sl@0:  * Results:
sl@0:  *	If string contains substring, the return value is the
sl@0:  *	location of the first matching instance of substring
sl@0:  *	in string.  If string doesn't contain substring, the
sl@0:  *	return value is 0.  Matching is done on an exact
sl@0:  *	character-for-character basis with no wildcards or special
sl@0:  *	characters.
sl@0:  *
sl@0:  * Side effects:
sl@0:  *	None.
sl@0:  *
sl@0:  *----------------------------------------------------------------------
sl@0:  */
sl@0: 
sl@0: char *
sl@0: strstr(string, substring)
sl@0:     register char *string;	/* String to search. */
sl@0:     char *substring;		/* Substring to try to find in string. */
sl@0: {
sl@0:     register char *a, *b;
sl@0: 
sl@0:     /* First scan quickly through the two strings looking for a
sl@0:      * single-character match.  When it's found, then compare the
sl@0:      * rest of the substring.
sl@0:      */
sl@0: 
sl@0:     b = substring;
sl@0:     if (*b == 0) {
sl@0: 	return string;
sl@0:     }
sl@0:     for ( ; *string != 0; string += 1) {
sl@0: 	if (*string != *b) {
sl@0: 	    continue;
sl@0: 	}
sl@0: 	a = string;
sl@0: 	while (1) {
sl@0: 	    if (*b == 0) {
sl@0: 		return string;
sl@0: 	    }
sl@0: 	    if (*a++ != *b++) {
sl@0: 		break;
sl@0: 	    }
sl@0: 	}
sl@0: 	b = substring;
sl@0:     }
sl@0:     return NULL;
sl@0: }