Josselin wrote:

/ ...

> and at the same time trying to understand how to USE srand()and rand(),
> my standard Ruby manual is clearly written but there is no example for
> this function.
> I googled a lot but without any success regarding examples...
> my first thought was:  srand() is useful in setting a limit to  the
> generator.... used by rand() so it could have been a clue to solve my
> problem...

All except you haven't yet said what the problem is. We could solve a stated
problem, easily.

srand() sets a particular starting point for a pseudorandom sequence. If you
use srand() and supply a fixed argument, you will get the same pseudorandom
sequence on each run of your program:

------------------------------------
#!/usr/bin/ruby -w

4.times do
   srand(1)
   10.times do
      print "#{rand(16)} "
   end
   puts
end
------------------------------------

Notice about this program that it puts out the same sequence every time. Now
comment out the "srand(1)" line and see the difference.

-- 
Paul Lutus
http://www.arachnoid.com