VBA Check if variable is empty

问题

I have an object and within it I wanna check if some properties is set to false, like:

If (not objresult.EOF) Then
  'Some code 
End if

But somehow, sometimes objresult.EOF is Empty, and how can I check it?

IsEmpty function is for excel cells only
objresult.EOF Is Nothing - return Empty
objresult.EOF <> null - return Empty as well!

回答1:

How you test depends on the Property's DataType:

| Type                                 | Test                            | Test2
| Numeric (Long, Integer, Double etc.) | If obj.Property = 0 Then        | 
| Boolen (True/False)                  | If Not obj.Property Then        | If obj.Property = False Then
| Object                               | If obj.Property Is Nothing Then |
| String                               | If obj.Property = "" Then       | If LenB(obj.Property) = 0 Then
| Variant                              | If obj.Property = Empty Then    |

You can tell the DataType by pressing F2 to launch the Object Browser and looking up the Object. Another way would be to just use the TypeName function:MsgBox TypeName(obj.Property)

回答2:

To check if a Variant is Null, you need to do it like:

Isnull(myvar) = True

Not Isnull(myvar)

回答3:

For a number, it is tricky because if a numeric cell is empty VBA will assign a default value of 0 to it, so it is hard for your VBA code to tell the difference between an entered zero and a blank numeric cell.

The following check worked for me to see if there was an actual 0 entered into the cell:

If CStr(rng.value) = "0" then
    'your code here'
End If

回答4:

I had a similar issue with an integer that could be legitimately assigned 0 in Access VBA. None of the above solutions worked for me.

At first I just used a boolean var and IF statement:

Dim i as integer, bol as boolean
   If bol = false then
      i = ValueIWantToAssign
      bol = True
   End If

In my case, my integer variable assignment was within a for loop and another IF statement, so I ended up using "Exit For" instead as it was more concise.

Like so:

Dim i as integer
ForLoopStart
   If ConditionIsMet Then
      i = ValueIWantToAssign
   Exit For
   End If
ForLoopEnd

来源：https://stackoverflow.com/questions/3329110/vba-check-if-variable-is-empty

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is-empty