Checking Data Types

Visual Basic has a number of data verification functions, which appear in Table 2.6, and you can use these functions to interrogate objects and determine their types.

Table 2.6: Type checking functions.
Function	Does this
IsArray()	Returns True if passed an array
IsDate()	Returns True if passed a date
IsDBNull()	Returns True if passed a database NULL value; that is, a System.DBNull value
IsError()	Returns True if passed an error value
IsNumeric()	Returns True if passed an numeric value
IsReference()	Returns True if passed an Object variable that has no object assigned to it; otherwise, returns False

Tip

You can also use the TypeOf keyword to get the type of an object like this: If (TypeOf Err.GetException() Is OverflowException) Then…. See "Making Decisions with If…Else Statements" in this chapter for more details.