PHP Type Comparison Table

The table below shows the role of PHP types and comparison operators when they are loosely and rigorously compared. The supplemental material is also relevant to the relevant section of the type-juggling. At the same time, a large number of user comments and»blueshoes work also provides help for this material.

Before using these tables, you need to understand the types of variables and their meanings. For example," A" is a string and a whole number is an integer. FALSEis a boolean value and "false" is a string.

Note:

HTML forms do not pass integers, floating-point numbers, or Boolean values, they only pass strings. To detect if a string is not a number, you can use the is_numeric () function.

Note:

When a variable is not defined $x , usage such as if ($x) results in a E_NOTICE level of error. Therefore, you might consider initializing the variable with the empty () or isset () function.

using PHP functions to $x compare variables

An expression	GetType ()	empty ()	is_null ()	isset ()	Boolean: if ($x)
$x = "";	String	TRUE	FALSE	TRUE	FALSE
$x = null;	Null	TRUE	TRUE	FALSE	FALSE
var $x;	Null	TRUE	TRUE	FALSE	FALSE
$xis undefined	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 = "1";	String	FALSE	FALSE	TRUE	TRUE
$x = "0";	String	TRUE	FALSE	TRUE	FALSE
$x = "1";	String	FALSE	FALSE	TRUE	TRUE
$x = "PHP";	String	FALSE	FALSE	TRUE	TRUE
$x = "true";	String	FALSE	FALSE	TRUE	TRUE
$x = "false";	String	FALSE	FALSE	TRUE	TRUE

PHP Type Comparison Table