string/strfry.c

   1 /* Copyright (C) 1992 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <string.h>
  21 #include <stdlib.h>
  22 #include <time.h>
  23
  24 char *
  25 DEFUN(strfry, (string), char *string)
  26 {
  27   static int init = 0;
  28   size_t len, i;
  29
  30   if (!init)
  31     {
  32       srand (time ((time_t *) NULL));
  33       init = 1;
  34     }
  35
  36   len = strlen (string);
  37   for (i = 0; i < len; ++i)
  38     {
  39       size_t j = rand () % len;
  40       char c = string[i];
  41       string[i] = string[j];
  42       string[j] = c;
  43     }
  44
  45   return string;
  46 }