# this program reads through a file 
# line by line and prints "PRINTING"
# for every line between $START & $STOP

# i'm intersted in improving my function &flip(\$flop)

$START = 'START';
$STOP = 'STOP';

$flop = 0;
while(<>) {
	my @record = split /,/;
	chomp($record[0]); 

	if (($flop) && ($record[0] ne $STOP)){
		print "PRINTING";
	} else {
		print "not printing";
	}
	if (($record[0] eq $START) || ($record[0] eq $STOP)) {
		&flip(\$flop);
	}
}

sub flip {$ref = @_[0]; $$ref = !($$ref)}	


##</code><code>##

$flop = !($flop)

##</code><code>##

sub flip { $@_[0] = !($@_[0] };