#!/usr/bin/perl -w

use strict;
my $data;
my $ERROR = 0;

# error();	# uncomment this to print $data before the loop

while ( (defined $data++) && everything_is_okay() ) {
    print "looping for the $data time.\n";
    if ( $data > 5 ) {
        $ERROR++;
        error();	# print $data if there's an error
    }
}
sub everything_is_okay {
    if ( $ERROR ) {
        print STDERR "ERROR LEVEL $ERROR\n";
        exit $ERROR;
    }
    return 1;
}
sub error {
    print $data;
}