More on the undefined variables problem. Would adding something like this do a loop be correct. 
while ($line0=<>) {$line1=<>;$line2=<>;$line3=<>;
last if not defined $line0;
last if not defined $line1;
last if not defined $line2;
last if not defined $line3;
do_some_stuff;
}

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Could I use some OR statements to get these last if-s on a single line. Or can or and and statements used only between two values. I was thinking like

 last if not defined $line0or$line1or$line2or$line3

or

 last if not defined $line0||$line1||$line2||$line3

In reply to Re^3: Reading files n lines a time by naturalsciences
in thread Reading files n lines a time by naturalsciences

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