quick PERL question

[David Gilden]

Dear Casey and the list,
Thanks for your all of your valuable help,

What is $|++ for?

#!/usr/local/bin/perl -w
use strict;
$|++;

while ( <DATA> ) {
  chomp; 
  print( &validate( $_ ) ? 'valid entry' : 'try again punk' );
  print "\n";
}

sub validate {
  my $currency = shift;

  # return false if we have an empty string or the string is just '$'.
  return 0 unless length( $currency ) > 0 && $currency ne '$';

  $currency =~ m<
                 ^      # The beginning of the string
                 \$?    # We may have a $ sign, we may not
                 \s*    # We may encounter some space here
                 \d*    # We may nave a numerator but could just have '.50'
                 (?:\.?\d{1,2})? # and we might have a denominator
                 $      # The end of the string
                >x ? 1: 0; # true if match succeeded, false otherwise
}

-----------

sub checkPrice{
return ($_[0] !~ /^\$?(\d+|\d*\.\d\d)$/) ? 1 : 0;
}

Is there a shorthand? Or do I need $_[0], 

---------

I could not seem to include the sub chekPrice in my if statement 

$x = &checkPrice($in{'price'});
if ( ($in{'name'} eq "") or
     ($in{'type'} eq "") or
     ($in{'price'} eq "") or 
     $x)

    {  .....
    
    
  ###  won't pass syntax validation!  
   if ( ($in{'name'} eq "") or
     ($in{'type'} eq "") or
     ($in{'price'} eq "") or 
     &checkPrice($in{'price'})
     )

    { ......

    

-----------

Are there any issues with using 
 if (!length $in{price}) ....
as opposed to:
if ($in{price} eq "") ...

I am not sure about !length, 
I mean it is not a $length, so it is not scalar is it some special variable?  
Thanks to [EMAIL PROTECTED] (Paul Johnson) for his input on this.

--------
Dave