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digitalmars.D.bugs - [Issue 1831] New: Random seeding appears not to work

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1831

           Summary: Random seeding appears not to work
           Product: D
           Version: 2.010
          Platform: PC
               URL: http://www.digitalmars.com/d/2.0/phobos/std_random.html
        OS/Version: Windows
            Status: NEW
          Severity: major
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: ig405 zepler.net


unpredictableSeed always returns the same value, across multiple runs and when
run in a loop.

seeding with rand() instead should in theory work, but my Random is always
returning the same sequence across multiple program runs. I have tried all the
methods in the documentation (see url) to no avail so I'd like to know if
anyone else has issues with this.

import std.random;
class Die{
  Random rnd;
  int value;
  int maxValue
  ...

  this()
  {
    ...
    Random rnd = Random(<seed>);
    roll();
  }
  int roll()
  {
    value = rnd.next() % maxValue;
    return value;
  }
}


--
Feb 13 2008
parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1831


andrei metalanguage.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID





unpredictableSeed works properly (except that it will be changed to return uint
instead of ulong in the next releast). You should just change your constructor
to:

this()
  {
    ...
    rnd = Random(<seed>);
    roll();
  }

so it doesn't define an automatic variable of the same name as the member.


--
Feb 13 2008