IsMissing returns False with non-Variant arguments [ All Languages » VB »  Language] Total Hit ( 3552) Rate this article:     Poor     Excellent   Submit Your Question/Comment about this article Rating

Every now and then I forget that the IsMissing function always returns False when the argument is not a Variant value. This happens because IsMissing does nothing more than converting its argument to Variant and testing for a special VarType value. For this reason, the following code is a symptom of a probable bug: Click here to copy the following block Sub DoSomething(Optional value As Long)  If IsMissing(value) Then   ' this code will be NEVER executed !!!  End If  '... End Sub Another little known quirk of the IsMissing function is that it always return False once the parameter has been set to an explicit value from within the procedure, as in: Click here to copy the following block Sub DoSomething(value1 As String, Optional value2 As Variant)  If IsMissing(value2) Then   value2 = value1  End If  '...  If IsMissing(value2) Then   ' this code will be NEVER executed !!!  End If  '... End Sub

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Submitted By : Nayan Patel  (Member Since : 5/26/2004 12:23:06 PM)
	Job Description : He is the moderator of this site and currently working as an independent consultant. He works with VB.net/ASP.net, SQL Server and other MS technologies. He is MCSD.net, MCDBA and MCSE. In his free time he likes to watch funny movies and doing oil painting.
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