perl -e "$c=qq(z);$d=qq(d); $c = $d++; $d = $c++; print $c,$d;"
ed

perl -e "$d=qq(d); $c = $d++; $d = $c++; print $c,$d;"
ed

##</code><code>##

perl -e "$d=qq(d); $c = $d; $d = $c++; print $c,$d;"
ed

##</code><code>##

perl -e "$c = $d = qq(d); $c++; print $c,$d;"
ed