note 118671 added to language.constants

Lets expand comment of 'storm' about usage of undefined constants. His claim that 'An undefined constant evaluates as true...' is wrong and right at same time. As said further in documentation ' If you use an undefined constant, PHP assumes that you mean the name of the constant itself, just as if you called it as a string...'. So yeah, undefined global constant when accessed directly will be resolved as string equal to name of sought constant (as thought PHP supposes that programmer had forgot apostrophes and autofixes it) and non-zero non-empty string converts to True. There are two ways to prevent this: 1. always use function constant('CONST_NAME') to get constant value (BTW it also works for class constants - constant('CLASS_NAME::CONST_NAME') ); 2. use only class constants (that are defined inside of class using keyword const) because they are not converted to string when not found but throw exception instead (Fatal error: Undefined class constant). ---- Server IP: 72.52.91.14 Probable Submitter: 93.85.29.7 ---- Manual Page -- http://php.net/manual/en/language.constants.php Edit -- https://master.php.net/note/edit/118671 Del: integrated -- https://master.php.net/note/delete/118671/integrated Del: useless -- https://master.php.net/note/delete/118671/useless Del: bad code -- https://master.php.net/note/delete/118671/bad+code Del: spam -- https://master.php.net/note/delete/118671/spam Del: non-english -- https://master.php.net/note/delete/118671/non-english Del: in docs -- https://master.php.net/note/delete/118671/in+docs Del: other reasons-- https://master.php.net/note/delete/118671 Reject -- https://master.php.net/note/reject/118671 Search -- https://master.php.net/manage/user-notes.php