Hi luckycat,

you could read the first line of the file outside of the main loop (before entering the loop). Something like this:

my $first_line = (<$IN>);
my $endofline = $first_line =~ /\r\n$/ ? "\r\n" : "\n";
# process first line ...
while (my $line = <$IN>) {
    # ...
}
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It makes the program a bit more complicated, because you need to process the first line separately, but it might be worth it if your file is really large. If the file has a moderate size, I would probably not care about trying to be more efficient by checking only once the end-of-line characters.