ZCE Notes - empty()

gistfile1.php

<?php

/*
 * Signature:   empty(mixed $var)
 * Description: A language construct to check if a *variable* is empty. 
 */

// The following variables are considered empty:

// * false
// * NULL
// * 0
// * 0.0
// * ''
// * array()
// * $someClass->declaredPropertyWithNoValue

// Usage
$thisVarIsEmpty = false;
$thisIsAString  = 'foo';

empty($thisIsAString);            // false!
empty($thisVarIsEmpty);           // true!
empty($thisVarDidNotExistBefore); // true! note... empty does not care if the var did not exist before.

// NOTE: empty will not like you if you try 
// to pass anything other than a var

define('SOME_CONSTANT', 1);

empty(SOME_CONSTANT); // parse error!
empty(array());       // parse error