Because $FH isn't a file handle - FILE is.

But beside that, you have more problems. You're not checking the return value of 'open', the file might not open. Furthermove, if you do: 

     while ((my $line_B = <FILE>)) {
         last OUTER unless defined ($line_B = <FILE>)

[download]
you will be skipping every odd line.
Perl --((8:>*

In reply to Re: readline() on unopened filehandle by Perl Mouse
in thread readline() on unopened filehandle by Win

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