re: repeatable random numbers in an object
re: repeatable random numbers in an object
- Subject: re: repeatable random numbers in an object
- From: "Mr. George Warner" <email@hidden>
- Date: Wed, 17 Jun 2009 08:51:26 -0700
On Wed, 17 Jun 2009 22:33:50 +0800, Roland King <email@hidden> wrote:
> I need to generate repeatable sequences of random numbers for a game.
> For each level I give it the seed and want the level to unfold the
> same way it did before. I can guarantee that the calls to any random
> function will be in exactly the same order, so provided I get the
same
> sequence out of the random generator, I'm good.
> First thought was to use srand() [ yes it's a bad random number
> generator but it's good enough for what want ] however it's global
and
> it's quite possible I'll have more than one 'level' running at the
> same time. So I need an object which I can give a seed to and will
> generate random numbers from that seed, and I need it to interoperate
> independently of any other object of the same type being queried for
> numbers.
term> man rand_r
...
The rand_r() function provides the same functionality as
rand(). A pointer to the context value seed must be
supplied by the caller.
The "pointer to the context value seed" can be a per-thread variable
so that different contexts don't interfere with each other. ;-)
--
Enjoy,
George Warner,
Schizophrenic Optimization Scientist
Apple Developer Technical Support (DTS)
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