declare empty variable

jtyson · April 8th, 2004, 10:41 AM

How do I declare a variable but leave it empty so I can check if it has been assigned a value later?

I have Dim intMyVar As Integer = nothing,

and then later I check it: If intMyVar = nothing Then

but it gives me the compilation error that Name intMyVar has not been declared.

In my code this variable may or may not be assigned a value, but I need it to exist and be able to check if it is empty or not.

Can someone show me the way?

Thanks,

John

Snib · April 8th, 2004, 10:57 AM

Could you set it to "", then check to see if it is "" or something else?

Snib

P2P Member
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Imar · April 8th, 2004, 11:02 AM

Hi John,

An Integer is a value type and will always be initialized to a default value of 0. So, even if you don't assign a value explicitly, the value is 0.

If 0 has no special meaning in your app, you can compare against that value. Often, -1 is used for this scenario as well.

Alternatively, you can assign Integer.MinValue or Integer.MaxValue to your int. If later in your app the Int still has that value, it hasn't been changed:

Code:

Dim i As Integer = Integer.MinValue
...
If i = Integer.MinValue Then
  ' Not changed
Else
  ' i has changed
End If

HtH,

Imar

---------------------------------------
Imar Spaanjaars
Everyone is unique, except for me.
While typing this post, I was listening to: Microphone Friend by Rage Against The Machine (Track 1 from the album: Renegades)