How to find Data Type of a Variable?

The data type of a variable can be indentified in two VBScript built-in functions.

1. Vartype 
   
2. Typename

Vartype returns a numeric value indicating the sub datatype of a variable.

The below table contains return values that indicate respective subtypes.

Return Value	Sub Datatype	Description
0	vbEmpty	Empty (uninitialized)
1	vbNull	Null (no valid data)
2	vbInteger	Integer
3	vbLong	Long integer
4	vbSingle	Single-precision floating-point number
5	vbDouble	Double-precision floating-point number
6	vbCurrency	Currency
7	vbDate	Date
8	vbString	String
9	vbObject	Automation object
10	vbError	Error
11	vbBoolean	Boolean
12	vbVariant	Variant (used only with arrays of Variants)
13	vbDataObject	A data-access object
17	vbByte	Byte
8192	vbArray	Array

Ex:

Dim x

x=10
msgbox vartype(x)  'Returns 2

In the above table 2 indicates vbInteger datatype.So x is an integer type.

Typename directly returns the name of the Sub Datatype of a variable.

Sub Datatype	Description
Byte	Byte value
Integer	Integer value
Long	Long integer value
Single	Single-precision floating-point value
Double	Double-precision floating-point value
Currency	Currency value
Decimal	Decimal value
Date	Date or time value
String	Character string value
Boolean	Boolean value; True or False
Empty	Unitialized
Null	No valid data
<object type>	Actual type name of an object
Object	Generic object
Unknown	Unknown object type
Nothing	Object variable that doesn't yet refer to an object instance
Error	Error

Ex:

Dim x

x=10
msgbox typename(x)  'Returns “Integer”

There are some more VBScript Built-in functions to find whether a variable datatype is specific datatype or not.

IsArray – Returns a Boolean value indicating whether a variable is an array or not.

IsDate – Returns a Boolean value indicating whether an expression can be converted to a date.

IsEmpty – Returns a Boolean value indicating whether a variable has been initialized.

IsNull - Returns a Boolean value that indicates whether an expression contains no valid data (Null).

IsNumeric - Returns a Boolean value indicating whether an expression can be evaluated as a number.

IsObject - Returns a Boolean value indicating whether an expression references a valid Automation object.

Built in functions are available for only these datatypes. You can write built function for every datatype like below…

'*******************************
Function IsString(oValue)

If vartype(oValue)=8 then

IsString=true
Else
IsString=False
End If
End Function
'*******************************