Name
IsError Function
Class
Microsoft.VisualBasic.Information
Syntax
IsError(expression
)
-
expression
Use: Required
Data Type: Object
An object variable that may be an Exception object
Return Value
Boolean (True
if
expression
is an Exception object,
False
otherwise)
Description
Indicates whether an object is an instance of the Exception class or one of its derived classes
Example
Module modMain Public Sub Main Dim oUnk As Object = "This is an object of subtype String." 'Dim oUnk As Object = 10 Dim oResult As Object = Increment(oUnk) If Not IsError(oResult) Then Console.WriteLine(oResult) Else Console.WriteLine(oResult.Message) End If End Sub Public Function Increment(o As Object) As Object If IsNumeric(o) Then o += 1 Return o Else Dim e As New System.InvalidOperationException Return e End If End Function End Module
VB .NET/VB 6 Differences
In VB 6, the IsError
function takes a variant
argument and determines if its subtype is vbError
.
Most commonly, it is used with the CVErr
function to determine if the value returned from a function is an
error. In VB .NET, the IsError
function is used
to test whether an object is an instance of the Exception class or
its derived classes.
See Also
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