use 5.020;
use Fcntl;
use strict;
use warnings;

my $file_name = 'C:\Windows\notepad.exe';

my $size = -s $file_name;
my ($data_open, $data_sysopen);

{
open my $fh1, '<', $file_name;
binmode $fh1;
local $/;
$data_open = <$fh1>;
close $fh1;
}

{
sysopen my $fh2, $file_name, O_RDONLY;
binmode $fh2;
read ($fh2, $data_sysopen, $size);
}

say "Groesse: ", $size;
say "Laenge gleich: ", length($data_open), ' | ' , length($data_sysopen);
say "Daten ", $data_open ne $data_sysopen ? 'ungleich' : 'gleich';