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All About Variables Part 3 : Checking for specific SubTypes
Part 1 | Part 2 | Part 3

There are six different functions that will assist you in determining if a particular variable is one Subtype or another. Below I have listed all of the SubType checking functions:


All of the above functions return a boolean value (true or false). Some of the above are self explanatory, however a few are not as clear. I will go over the ones that need explaining:

     What makes a variable empty? If the variable has been created, but has not been assigned a value yet it is considered to be empty. This is different from a value that is empty ("") or equal to NULL.

     What makes a variable null? A variable is null only when it equals null. You can set a variable equal to null.

This will return true if the variable can be converted to a numeric SubType without generating an error.


myVar = "Hello"
If IsNumeric(myVar) Then
     Response.Write("Variable is numeric.")
Else      Response.Write("Variable is NOT numeric.")
End If

Variable is NOT numeric.

Another way to determine the variable SubType is the VarType() function.


The above function will return a number representing the various subtypes. I have listed them for you below:

Subtypes Value Description
vbEmpty 0 Not assigned a value
vbNull 1 No matching SubType
vbInteger 2 Integer
vbLong 3 Long
vbSingle 4 Single
vbDouble 5 Double
vbCurrency 6 Currency
vbDate 7 Date
vbString 8 String
vbObject 9 Object
vbError 10 Error
vbBoolean 11 Boolean (true or false)
vbVariant 12 Variant, array of variants only
vbDataObject 13 Data Access
vbDecimal 14 Decimal
vbByte 17 Byte
vbArray 8192 Array