Atlanta Custom Software Development 

 
   Search        Code/Page
 

User Login
Email

Password

 

Forgot the Password?
Services
» Web Development
» Maintenance
» Data Integration/BI
» Information Management
Programming
  Database
Automation
OS/Networking
Graphics
Links
Tools
» Regular Expr Tester
» Free Tools

IsMissing returns False with non-Variant arguments

Total Hit ( 2444)

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


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.
View all (893) submissions by this author  (Birth Date : 7/14/1981 )


Home   |  Comment   |  Contact Us   |  Privacy Policy   |  Terms & Conditions   |  BlogsZappySys

© 2008 BinaryWorld LLC. All rights reserved.