The Ruby Way: Solutions and Techniques in Ruby Programming, Second Edition

5.28. Generating Random Numbers

If a pseudorandom number is good enough for you, you’re in luck. This is what most language implementations supply you with, and Ruby is no exception.

The Kernel method rand returns a pseudorandom floating point number x such that x>=0.0 and x<1.0. For example (note yours will vary)

a = rand      # 0.6279091137

If it is called with an integer parameter max, it returns an integer in the range 0...max (noninclusive of the upper bound). For example (note yours will vary)

n = rand(10)  # 7

If we want to seed the random number generator, we can do so with the Kernel method srand, which takes a single numeric parameter. If we pass no value to it, it will construct its own using (among other things) the time of day. If we pass ...