Visual Basic.NET
Visual Basic.NET

Operator '=' is not defined for type 'DBNull' and type 'Integer'

I am migrating vb6 project to vb.net. there are variant type arrays that I migrated as object types.
having this code line I get the error: Operator '=' is not defined for type 'DBNull' and type 'Integer'
If arrY(13, X) = gloT And (CBool(arrY(18, X)) = True Or (CBool(arrY(18, X)) = False And arr(65, X) = 100)) Then
arr(65, X) has a null value . If I cannt initialize it to 0 how can I avoid the exception?

Miss leahdeveloper & project managerAsked: 2018-11-14

Who is Participating?

Experts Exchange Solution brought to you by

Enjoy your complimentary solution view.

Get this solution by purchasing an Individual license! Start your 7-day free trial.

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

LVL 22

Peter HutchisonSenior Network Systems SpecialistCommented: 2018-11-14

To be honest, it would be best practise try to avoid using Object when migrating to VB.Net and you should always initialise arrays before using them, as you cannot guarantee what is in the values before using them.

e.g.
Dim arr(100,100) as Integer
Dim r as integer, c as integer

For r=1 to 100
For c=1 to 100
arr(r,c)=0
Next c
Next r

Alternatively, you could modify the values in the condition:

f arrY(13, X) = gloT And (CBool(arrY(18, X)) = True Or (CBool(arrY(18, X)) = False And (arr(65, X) + 0) = 100)) Then

Miss leahdeveloper & project managerAuthor Commented: 2018-11-14

Thank you, I initialize the array but the vb6 code is using the null value after the initialize to 0. I assume there is a significance to that. I tried to use +0 method you mentioned but still getting the error: Operator '+' is not defined for type 'DBNull' and type 'Integer'

LVL 22

Peter HutchisonSenior Network Systems SpecialistCommented: 2018-11-14

How do you set up the values from the array, do you read them from a database or a file.

I find that, you should read values as strings (add a empty string to covert from Null to a value) and then try to convert to a integer value (using VAL or CInt or whatever) before assigning to the array.

LVL 65

Fernando SotoRetiredCommented: 2018-11-14

Hi Hagar;

The DbNull is the a non existent value used in databases for not having a value. When you attempt to use a variable that may contain a DbNull you need to test to see if the variable has a valid value first. Something like the following can be used.

Dim arr65 = If( DBNull.Value.Equals(arr(65, X)), 0, arr(65, X))
If arrY(13, X) = gloT And (CBool(arrY(18, X)) = True Or (CBool(arrY(18, X)) = False And arr65 = 100)) Then

Open in new window

What this does is check to see if arr(65, X) has a valid value if it is a DBNull it assign 0 to the variable arr65 other wise it assigns the valid value to arr65.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial