[erlang-questions] Bug using negative numbers to crypto:rand_uniform?
Jesper Louis Andersen
Tue Jul 8 17:19:44 CEST 2008
I've tried the following in R11B-5 and had people check it in R12B
(subrevision unknown) as well:
Calls of the form
Where Lo and Hi are negative integers fail due to some wrap-around somewhere:
()12> crypto:rand_uniform(-10, -5).
The documentation states:
rand_uniform(Lo, Hi) -> N
Lo, Hi, N = Mpint | integer()
Mpint = binary()
Generate a random number N, Lo =< N < Hi. Uses the crypto library
pseudo-random number generator. The arguments (and result) can be
either erlang integers or binary multi-precision integers.
Which doesn't mention anything about negative integer() values. Other
interesting test cases are combinations of negative and positive
numbers and where Lo > Hi etc. It is rather easy to work around, but
either the documentation or the implementation should be changed to
solve the problem in my humble opinion.
Finally: Should this go to erlang-bugs@ intead? Or is that I just
can't read the documentation?
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