[swift-users] Make getting a random number more intuitive
Jens Alfke
jens at mooseyard.com
Thu Jan 21 15:24:09 CST 2016
> On Jan 21, 2016, at 1:00 PM, Erica Sadun via swift-users <swift-users at swift.org> wrote:
>
> * In terms of cross-platform random numbers, there are any number of third party libraries and you can use rand() on many platforms
rand() is deprecated because it uses a poor algorithm that doesn’t provide enough randomness. From the random(3) man page:
The random() and srandom() functions have (almost) the same calling
sequence and initialization properties as the rand(3) and srand(3) func-
tions. The difference is that rand(3) produces a much less random
sequence -- in fact, the low dozen bits generated by rand go through a
cyclic pattern. All of the bits generated by random() are usable. For
example, `random()&01' will produce a random binary value.
I’d forgotten that random()s sidekick function srandomdev() seeds the RNG with a cryptographic source of entropy, making it usable for secure purposes. So these would be good functions to implement a Swift RNG with.
—Jens
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