----- Original Message -----
From: "Ted Schuerzinger" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, December 02, 2005 2:53 AM
Subject: Hash limits? (Was: Re: rand() not so random)
> [EMAIL PROTECTED] (Chris Wagner) graced perl with these words of
> wisdom:
>
> > Just for fun I did a little test.
> > for (1 .. 10000) {
> > my $fn = rand();
> > ++$dup and next if exists $num{$fn};
> > $num{$fn} = 1;
> > }
> > print scalar keys %num, " unique numbers. $dup duplicates produced\n";
> >
>
> Just for fun, I changed one of the lines in that to
>
> for (1 .. 1000000) {
>
> When I ran the modified script, I got 32768 unique numbers, with 967232
> duplicates! As 32768 is a power of 2, I'm wondering if there's a limit on
> the number of keys one may have in a hash.
>
I think it's just that there are only 2 ** $Config{randbits} distinct
numbers that rand() will output.
You'll probably find that $Config{randbits} for you is 15 .... and 2 ** 15
== 32768.
ie, with 15 bits, you can represent only 32768 different numbers.
Cheers,
Rob
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