--- C ---
m=20; ++m + m++ is 42
m=20; noop(++m) + m++ is 42

 --- Java ---
m=20; ++m + m++ is 42
m=20; noop(++m) + m++ is 42

 --- Perl ---
$m=20; ++$m + $m++ is 43          <===== ! 
$m=20; noop(++$m) + $m++ is 42