There is in the second method posted by james28909: 

my $data = do {

    local $/ = undef;
    open (my $fh, "<", $input_file) or die "could not open $input_file
+: $!";
    binmode($fh);
    <$fh>;

};

my $reversed_data = pack( "v*", unpack( "n*", $data ) );

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But since it's not copied from one variable to another, it probably makes little difference indeed, I didn't think it through.

In reply to Re^3: Fastest byteswap (little endian to big endian (eg. 34127856 -> 12345678) by Eily
in thread Fastest byteswap (little endian to big endian (eg. 34127856 -> 12345678) by james28909

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