Good advice, Masem. But your if statement example doesn't work ...

do { # not without the do
    $lowrange = 0; 
    print "\nYour number must be positive. I have set it to 0 for you.
+"; 
} if ($lowrange < 0);
[download]

this form of if (or unless, foreach, while, until) only works on simple statements, not on blocks.

-- Hofmator