FunkyMonk: this may do the trick

try:

my $percent = 10;
my $string = 'A' x 1_000_000;

for ( 1 .. $percent / 100 * length $string ) {
    my $pos = int rand length $string;
    substr( $string, $pos, 1 ) = '?';
}
print $string =~ y/?//;
[download]

Sth. like this is the approach I initially took (and failed).

If you check that out (with a larger string), youll see the print-
out from the last line will approach 0xffff.

That means (I'm struggling to say this)

   In Activeperl/Win, the RAND_MAX of 
   the underlying clib is promoted 
   into perl?

Is this documented?

Regards & Thanks

mwa