Question

define('EMPTY', '');
if(!empty(EMPTY))
{
if(!(boolean) _CONSTANT)
{
    print "One";
}
}

The above code produces the following error message:

“Parse error: syntax error, unexpected ‘EMPTY’ (T_EMPTY) in C:\Users\Robert\Documents\web development\xampp\htdocs\xampp\web_development\index.php on line 3”

Nowhere in the PHP Manual does it explicitly state that “EMPTY” is a token nor does it inform you about this pitfall.

Answer 1

Function names are case insensitive.

$state = constant('EMPTY');
if (!empty($state)) {