stdlib/testrand.c

   1 /* Copyright (C) 1992-2021 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 Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the 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    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <stdlib.h>
  19 #include <stdio.h>
  20
  21 int
  22 main (void)
  23 {
  24   int i1, i2;
  25   int j1, j2;
  26
  27   /* The C standard says that "If rand is called before any calls to
  28      srand have been made, the same sequence shall be generated as
  29      when srand is first called with a seed value of 1." */
  30   i1 = rand();
  31   i2 = rand();
  32   srand (1);
  33   j1 = rand();
  34   j2 = rand();
  35   if (i1 < 0 || i2 < 0 || j1 < 0 || j2 < 0) {
  36       puts ("Test FAILED!");
  37   }
  38   if (j1 == i1 && j2 == i2)
  39     {
  40       puts ("Test succeeded.");
  41       return 0;
  42     }
  43   else
  44     {
  45       if (j1 != i1)
  46         printf ("%d != %d\n", j1, i1);
  47       if (j2 != i2)
  48         printf ("%d != %d\n", j2, i2);
  49       puts ("Test FAILED!");
  50       return 1;
  51     }
  52 }