if(exists $userhash{$username}) {
        $userhash{$username}++;
      }
      else{
        $userhash{$username}=1 ;
      }

##</code><code>##

      $userhash{$username}++;

##</code><code>##

open( INPUTDATAFILE, "< $inputfile" ) or die ...

##</code><code>##

open my $inputdatafile, '<', $inputfile or die ...