use Encode qw(encode decode);

while ( my $readline = <$fh> ){
   my $foo   = decode('UTF-8', $readline);
}


##</code><code>##

use Encode qw(encode decode);

while ( my $readline = <$fh> ){
    my $foo = decode('UTF-8', $readline);
    #do stuff here 
    $foo = encode('UTF-8', $foo);
    print {$output_fh} $foo;
}