glibc/stdlib/testrand.c

/* Copyright (C) 1992-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <stdlib.h>
#include <stdio.h>

int
main (void)
{
  int i1, i2;
  int j1, j2;

  /* The C standard says that "If rand is called before any calls to
     srand have been made, the same sequence shall be generated as
     when srand is first called with a seed value of 1." */
  i1 = rand();
  i2 = rand();
  srand (1);
  j1 = rand();
  j2 = rand();
  if (i1 < 0 || i2 < 0 || j1 < 0 || j2 < 0) {
      puts ("Test FAILED!");
  }
  if (j1 == i1 && j2 == i2)
    {
      puts ("Test succeeded.");
      return 0;
    }
  else
    {
      if (j1 != i1)
	printf ("%d != %d\n", j1, i1);
      if (j2 != i2)
	printf ("%d != %d\n", j2, i2);
      puts ("Test FAILED!");
      return 1;
    }
}