Re: [Boost-users] random number generator 160 bit.

From: james.jones_at_[hidden]
Date: 2006-08-09 16:53:35

From: "chun ping wang" <cablepuff_at_[hidden]>
> [code skipped]
>   T n(Random::randint<T>(numeric_cast<T>(pow(2.0, num_digits - 1)),
>                          numeric_cast<T>(pow(2.0, num_digits)))
> [code skipped]
>
> now num_digits is number of bits. If i pass 160 bit as like for DSA
> algorithm the program crashes. I pass 8 and it works, how come? Is there a
> better way to do this? Oh f is any function that can deteremine if a number
> is most likely a prime or not....

My guess is that numeric_cast<T>(pow(2.0, num_digits)) throws an overflow exception. I don't know what you're using for T, but obviously even a long long can't hold a 160-bit integer (at least not on any architecture I'm aware of).

To verify this, catch on overflow_error and see if this prevents the crash.

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