Say what? That's the same as this:

$argument = undef;
while (0)
{
}
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This is the noise you'll be making when you try and run that program: "ARVG! ARVG!"

Remember, when pushing buttons on the keyboard, it is important to hit them in the right order. Must be one of those late nights/early mornings?

I think what you meant was:

$|++;

my $argument = $ARGV[0] || warn "No argument given\n";

do
{
    print "Enter an argument: ";
    chomp ($argument = <STDIN>);
} while (!length($argument));
[download]