Is this a piece of cake for you? Then check the PHP Syntax Exam :-)

The PHP Documentation Group has now added the Appendix K. PHP type comparison tables to the official PHP manual.

Empty() & Co, Special Values

	gettype()	empty()	is_null()	isSet()	(bool)
$x = "";	string	true	false	true	false
$x = null;	NULL	true	true	false	false
var $x; (not set)	NULL	true	true	false	false
$x = array();	array	true	false	true	false
$x = false;	boolean	true	false	true	false
$x = 15;	integer	false	false	true	true
$x = 1;	integer	false	false	true	true
$x = 0;	integer	true	false	true	false
$x = -1;	integer	false	false	true	true
$x = "15";	string	false	false	true	true
$x = "1";	string	false	false	true	true
$x = "0";	string	true	false	true	false
$x = "-1";	string	false	false	true	true
$x = "foo";	string	false	false	true	true
$x = "true";	string	false	false	true	true
$x = "false";	string	false	false	true	true

Note: empty() and isSet() don't give a warning when the variable has not been defined before.

The Index Server indexes text coming from websites, files, db tables etc to perform fast fulltext queries. It supports boolean operators, "fixed strings", stemming ... more