• Clay Bridges (7/7) Dec 29 2010 I see code like this:
• Stewart Gordon (12/17) Jan 04 2011 Yes. Since 8 has only one set bit, there are only two possible values -...

Clay Bridges <diffengr gmail.com> writes:

I see code like this:

  if (ranq() & 8) ...

where ranq() is defined as

  uint ranq() { return std.random.rand(); }

Would that be a coin toss, and similar to , e.g. (ranq() & 1)?

Thanks

Clay

Stewart Gordon <smjg_1998 yahoo.com> writes:

On 29/12/2010 22:41, Clay Bridges wrote:
 I see code like this:

    if (ranq()&  8) ...

 where ranq() is defined as

    uint ranq() { return std.random.rand(); }

Good question - why is this wrapper there?

 Would that be a coin toss, and similar to , e.g. (ranq()&  1)?

Yes.  Since 8 has only one set bit, there are only two possible values - 
0 and 8.

I don't know why 8 was chosen.  I just searched the code and found 
instances of:

     ranq() & 1  (1/2 chance)
     ranq() & 4  (1/2 chance)
     ranq() & 8  (1/2 chance)
     ranq() & 7  (1/8 chance)
     ranq() & 15 (1/16 chance)

Stewart.