primitive types and ckecking functions in PHP

Type Checking	Function	Type Description
is_bool()	Boolean	one of the two special values true or false
is_integer()	Integer	A whole number
is_double()	Double	A floating point number (a number with a decimal point)
is_string()	String	Character data
is_object()	Object	An object
is_array()	Array	An Array
is_resource()	Resource	A handle for identifying and working with external resources such as databases or files
is_null()	NULL	an unassigned value