$counter->lock;

$counter->dec while $counter->value > $DEFAULT_VALUE;

$counter->unlock;

##</code><code>##

sub reset {   
    my($self,$default) = @_;

    $default = $File::CounterFile::DEFAULT_INITIAL 
        unless defined $default;
    
    if ($self->locked) {
        $self->{'value'} = $default;
        $self->{updated} = 1;
    } else {
        $self->lock;
        $self->{'value'} = $default;
        $self->{updated} = 1;
        $self->unlock; 
    }
    $self->{'value'}; # return value
}

##</code><code>##

#!/usr/bin/perl -w

use strict;
use File::CounterFile;

my $COUNTER       = '/path/to/bg.cnt';
my $DEFAULT_VALUE = 0;

my @BACKGROUND    = qw(
  corner.jpg    anduin.jpg    gandalf.jpg  
  ford.jpg
);

my $c = File::CounterFile->new( $COUNTER, $DEFAULT_VALUE );
   $c->reset if $c->inc > $#BACKGROUND;

print <<EndOfHTML;
Content-type: text/html

<td background="images/$BACKGROUND[$c]">
EndOfHTML