How to determine the type of a variable in PHP

There are various types of variables in PHP, different types have different ways of judging, here is a summary of some of the types of variables in PHP judgment.

First, GetType ()
GetType returns the following values based on the parameter type
"Boolean" (from PHP 4)
"Integer"
"Double" (If float returns "Double" instead of "float")
"String"
"Array"
"Object"
"Resource" (from PHP 4)
"NULL" (from PHP 4)
"Unknown type"

For example:
GetType (' 1 '); Returns a string
and GetType (1); Returns an integer

Second, the type of PHP self-judgment is as follows

Isset ():                        ///variable declared empty ():                        //variable is empty defined ():///The constant has been defined define () array_key_exists (mixed key , array Search)://        Check whether the given key name or index exists in the array is_numeric (mixed var):                //Detection variable is a numeric or numeric string Is_bool ():            // Check whether the variable is Boolean is_float ():            //The use of the detection variable is floating point and is_double,is_real () are the same usage is_int ():            //Detection variable is an integer Is_integer () the same usage is_ String ():            ///detects if the variable is a string Is_object ():            //detects if the variable is an object Is_array ():            //detects if the variable is an array is_null ():            //The detection variable is Null value is null case sensitive

Three, PHP empty, isset, isnull difference

Empty

If the variable is a non-null or nonzero value, empty () returns FALSE. In other words, "", 0, "0″, NULL, FALSE, Array (), Var $var, undefined, and objects that do not have any properties will be considered empty, and if Var is null, it returns TRUE."

Isset

Returns TRUE if the variable exists (not null), otherwise FALSE (including undefined). The variable value is set to: null, and the variable is canceled after the return is also false;unset a variable. Note that isset for null value variables, special handling.

Is_null

Detects if the passed-in value "value, variable, expression" is null, only one variable is defined, and its value is NULL, it returns TRUE. All others return FALSE "an undefined variable is passed in with an error!" 】