Re: [boost] Strange use of random values in regression test ...

Subject: Re: [boost] Strange use of random values in regression test ...
From: Thijs van den Berg (thijs_at_[hidden])
Date: 2014-04-21 13:34:20

On 21 Apr 2014, at 18:55, Chris Cooper <chris.cooper_at_[hidden]> wrote:

> The test_main() of libs/utility/operators_test.cpp loops 1000 times, running a variety of tests on random values.  However, since the randomizer (boost::minstd_rand) is instantiated inside the loop, it appears that the randomizer is re-seeded for each loop, meaning it runs the test 1000x with the exact same values each time.
> 
> I’m not 100% familiar with the boost random value generators, am I missing something?  Or should the boost::minstd_rand be instantiated outside the loop?
> 
> I’m happy to add this as a boost bug if my understanding is correct …
> 
> Thanks,
> Chris

Yes you need to put it outside the loop. When the random object is created it’s set to the same default seed.