Re: Lotto simulation

[Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org>]

On 06/15/2014 10:07 AM, montgrimpulo wrote:
>
> this is a placeholder of the task which I am trying to solve in Ada.
> As you may know in German Lotto there are 49 numbers 1..49
> from which you have to select 6 numbers to place a bet.

I would usually define

type Lotto_List is array (T1_49) of T1_49;

List : Lotto_List;

Then fill List so that it contains (1 => 1, 2 => 2, 3 => 3, ...).

Then, for I in List'range, select a random Index, and swap the values in I and 
Index. Finally, use the values in List (1 .. 6).

That doesn't have the same probabilities as picking 6 balls out of 49. If you 
want that, you have to do

for I in List'First .. List'Last - 1 loop
    select random Index in I + 1 .. List'Last
    swap I and Index
end loop;

which is a little more complex if you use Discrete_Random. The random number 
generators in the PragmAda Reusable Components all come with functions to return 
a value in an integral range, so I generally use one of them rather than one of 
the predefined generators.

http://pragmada.x10hosting.com/pragmarc.htm

-- 
Jeff Carter
"This trial is a travesty. It's a travesty of a mockery of a
sham of a mockery of a travesty of two mockeries of a sham. ...
Do you realize there's not a single homosexual on that jury?"
Bananas
27