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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.

 *

 * RCS: @(#) $Id: strstr.c,v 1.1.1.1 2002-01-16 10:25:23 markom Exp $

 */

/*

 *----------------------------------------------------------------------

 *

 * 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;

}