问题
One of my cells appears to be blank but has a length of 2 characters. I copied the string to this website and it has identified it as a null string.
I have tried using IsNull and IsEmpty, as well as testing to see if it is equivalent to the vbNullString but it is still coming up as False.
How do I identify this string as being Null?
回答1:
A string value that "appears to be blank but has a length of 2 characters" is said to be whitespace, not blank, not null, not empty.
Use the Trim function (or its Trim$ stringly-typed little brother) to strip leading/trailing whitespace characters, then test the result against vbNullString (or ""):
If Trim$(value) = vbNullString Then
The Trim function won't strip non-breaking spaces though. You can write a function that does:
Public Function TrimStripNBSP(ByVal value As String) As String
TrimStripNBSP = Trim$(Replace(value, Chr$(160), Chr$(32)))
End Function
This replaces non-breaking spaces with ASCII 32 (a "normal" space character), then trims it and returns the result.
Now you can use it to test against vbNullString (or ""):
If TrimStripNBSP(value) = vbNullString Then
The IsEmpty function can only be used with a Variant (only returns a meaningful result given a Variant anyway), to determine whether that variant contains a value.
The IsNull function has extremely limited use in Excel-hosted VBA, and shouldn't be needed since nothing is ever going to be Null in an Excel worksheet - especially not a string with a length of 2.
回答2:
Chr(160) Issue
160 is the code number of a Non-Breaking Space.
Let us say the cell is A1.
In any cell write =CODE(A1) and in another (e.g. next to) write =CODE(MID(A1,2,1)).
The results are the code numbers (integers e.g. a and b) of the characters.
Now in VBA you can use:
If Cells(1, 1) = Chr(a) & Chr(b) Then
End If
or e.g.
If Left(Cells(1, 1), 1) = Chr(160) then
End If
来源：https://stackoverflow.com/questions/54204067/vba-identifying-null-string