“boolean和include ..”但是“boolean and unset（$ v）”报告PHP中的语法错误？

Question

This works:

!function_exists('testfunc') and include("testfunc.php");

This will report syntax error:

!function_exists('testfunc') and unset($q);

Aren't they the same thing?

Answer 1

unset has no return value and according to http://php.net/manual/en/function.include.php you can "return" from the included file (so it's not void :P)

...I'm pretty sure that's what it is