Invalidcastexception occur when i try to upgrade vb6 to .net any help appreciate...

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VB

'FIXIT: Declare 'varValue' with an early-bound data type                                   FixIT90210ae-R1672-R1B8ZE
Public Function NullToText(varValue As Variant) As String

    ' Append an empty string, forcing a conversion
    ' of a Null value to a string, leaving normal
    ' strings as is.
    NullToText = varValue & vbNullString

End Function

Posted 23-Dec-11 9:36am

Tony Radu

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Wendelius · Answer 1 · 2011-12-23T10:26:00

What is exactly that you're trying to do? First of all, basically all objects have ToString()[^] method since it's defined on Object class and derived on all other classes.

If you're wondering what is the equivalent for variant, use object.

If the problem lies in conversion if varValue is Nothing, then you could use something like:

VB

Public Function NullToText(varValue As Object) As String
    If varValue Is Nothing Then
        NullToText = ""
    Else
        NullToText = varValue.ToString()
    End If
End Function

However, depending on your environment and what you use this function for, that may not work correctly if decimal numbers, dates etc. are passed to the function and different locales are used since the conversion should be culture aware. For example, see: Int32.ToString Method (IFormatProvider)[^]