PHP Comparison between double, triple equals with useful functions

Thursday, May 12, 2011 EDT

by: Eric Potvin

Tags:php

Here's a quick table that will help you to find out quickly how PHP compares and use is types.

Functions comparison:

expression	gettype()	empty()	is_null()	isset()	boolean test: if($x)
$x = ''	string	TRUE	FALSE	TRUE	FALSE
$x = NULL	NULL	TRUE	TRUE	FALSE	FALSE
$x = array()	array	TRUE	FALSE	TRUE	FALSE
$x = FALSE	boolean	TRUE	FALSE	TRUE	FALSE
$x = TRUE	boolean	FALSE	FALSE	TRUE	TRUE
$x = 1	integer	FALSE	FALSE	TRUE	TRUE
$x = 42;	integer	FALSE	FALSE	TRUE	TRUE
$x = 0	integer	TRUE	FALSE	TRUE	FALSE
$x = -1	integer	FALSE	FALSE	TRUE	TRUE
$x = '90'	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 = 'awesome'	string	FALSE	FALSE	TRUE	TRUE
$x = 'TRUE'	string	FALSE	FALSE	TRUE	TRUE
$x = 'FALSE'	string	FALSE	FALSE	TRUE	TRUE
$x is undefined	NULL	TRUE	TRUE	FALSE	FALSE

Comparaison using ==

	TRUE	FALSE	1	0	-1	'1'	'0'	'-1'	NULL	array()	string
TRUE	TRUE	FALSE	TRUE	FALSE	TRUE	TRUE	FALSE	TRUE	FALSE	FALSE	TRUE
FALSE	FALSE	TRUE	FALSE	TRUE	FALSE	FALSE	TRUE	FALSE	TRUE	TRUE	FALSE
1	TRUE	FALSE	TRUE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE
0	FALSE	TRUE	FALSE	TRUE	FALSE	FALSE	TRUE	FALSE	TRUE	FALSE	TRUE
-1	TRUE	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE
'1'	TRUE	FALSE	TRUE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE
'0'	FALSE	TRUE	FALSE	TRUE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE
'-1'	TRUE	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE
NULL	FALSE	TRUE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	TRUE	TRUE	FALSE
array()	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE	TRUE	FALSE
'string'	TRUE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE

Comparaison using ===

	TRUE	FALSE	1	0	-1	'1'	'0'	'-1'	NULL	array()	string
TRUE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE
FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE
1	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE
0	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE
-1	FALSE	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE
'1'	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE	FALSE
'0'	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE	FALSE
'-1'	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE	FALSE
NULL	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE	FALSE	FALSE
array()	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE	FALSE
'string'	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	FALSE	TRUE

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