Thanks for the reply, I tried implementing your suggestion of using a pair of iterators, but I think that I might be misinterpreting the source, and that it is still only using a 32-bit seed.

From looking at the source, the seed appears to be stored as the variable "i", which is of type int.  The seed method using two iterators does a ton of mangling over the range, and assigned i to the result.

Am I misreading the source here, or no matter what I do, am I stuck with a 32 bit seed?

If so, is there a more suitable method to do what I am trying to accomplish?  I really need the seed to be (at least) 64 bits.

On Tue, Feb 24, 2009 at 9:28 PM, Steven Watanabe <watanabesj@gmail.com> wrote:
AMDG


James Madison wrote:
I am currently developing a distributed application where many clients need to generate unique 64-bit random numbers which will be used as keys.  I am having problems getting boost to do this.  For my first attempt, I tried something like the following:

       boost::mt19937 RandomNumberGenerator::s_algorithm;

       boost::uniform_int<unsigned long long> RandomNumberGenerator::s_range(
           std::numeric_limits<unsigned long long>::min(), std::numeric_limits<unsigned long long>::max());

       boost::variate_generator<boost::mt19937&, boost::uniform_int<unsigned long long> >
           RandomNumberGenerator::s_rng(RandomNumberGenerator::s_algorithm, RandomNumberGenerator::s_range);

I had two issues though:

1.  Is this really giving me random 64 bit numbers, or is it just generating 32-bit numbers and then doing bit expansion?

mt19937 generates 32 bit integers.  uniform_int combines multiple invocations
of the underlying PRNG if necessary.


2.  The values always started with the same number.

Trying to find a fix for #2, I though of using a hashed GUID as a seed.  The problem is I noticed the seed value takes a 32 bit int, which essentially means a 1/2^32 chance of the first value colliding even if chosen completely randomly, which is unacceptable for my application.

There is also seed functions which takes a pair of iterators.

In Christ,
Steven Watanabe

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