~$ echo '<?php echo empty("foo"); ?>' > test.php
~$ php3 test.php
X-Powered-By: PHP/3.0.18
Content-type: text/html

<br>
<b>Parse error</b>:  parse error, expecting `'$'' in <b>test.php</b> on line <b>1</b><br>
~$ php43 test.php

Parse error: parse error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting T_VARIABLE or '$' in /home/arpad/test.php on line 1
~$ php44 test.php

Parse error: parse error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting T_VARIABLE or '$' in /home/arpad/test.php on line 1
~$ php test.php

Parse error: syntax error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting T_STRING or T_VARIABLE or '$' in /home/arpad/test.php on line 1