It really depends on how you open the file. The best way in 5.8+ is probably

# Raw buffered handle.
open(my $fh, '<:perlio', $qfn)
   or die("open $qfn: $!\n");
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For compatibility with 5.6, you'd use

open(my $fh, '<', $qfn)
   or die("open $qfn: $!\n");
binmode($fh);
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In both case, you only get bytes, so "C" is perfectly acceptable.