Author: Severi Salminen
Date: 13:15:49 11/04/02
Go up one level in this thread
>No, binary or does also not guarantee the order in which the different parts are
>called. You are thinking of logical or.
You are absolutely correct, thanks. I mixed those two. Maybe _I_ should read
that "sequence point" topic more carefully :)
>>unsigned __int64 rand64()
>>{
>> return (ui) rand()|(ui)rand()<<15|(ui)rand()<<30 //and so on...
>>}
>
>
>It is even worse. There is no guarantee, that rand() returns exactly 15 bits
>(there is a guarantee, that it returns at least 15 bits). So, if an
>implementation will return (say) 31 bits, you will have in average much more set
>bits in the 64 bit number, than 0 bits. Not very random ...
>When using xor, it at least gives something rather random looking back.
True, again. Now we see results when one posts before activating that brain
thingy...For some reason I thought that rand() returns 15 bits, exactly...
>I also agree with all the other posters, who suggest to use your own PRNG or use
>a program generated table.
Yes, own rand() is the best solution. No need to guess what it is doing. And no
need to include precompiled random number array.
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