PJ on Development

That's THE strangest bug I ever encountered while working with Visual Basic. Ever!

I was parsing a list of strings that was separated by a CR/LF pair. Something like this:

The quick brown fox jumped over the lazy dog.[CR][LF]
Miss Piggy sent Kermit an email.[CR][LF]
Lois was cheating on Clark[CR][LF]

So, I used the following command to get an array of strings:

Dim aStrList as String() = _
           strFullList.Replace(vbLf, "").Split(vbCr)

Simple, right?

And then I went to my loop:

For Each strItem As String In aStrList
    If (strItem = "") Then
        Exit For
    End If

    '... do whatever...
Next

The first time I ran it it crashed my code. I took me some time to discover why.

Apparently the last item of the array, instead of being and empty string, is a String which contains a single "character" Nothing.

The ONLY way I could find to workaround this stuff was changing my test line to look like this:

If (strItem.Chars(0) = Nothing) Then

For the sake of completion, this strange string has the following properties:

Test	Result
strItem = ""	False
strItem = Nothing	False
strItem.Length = 0	False
strItem.Length = 1	True

However when examined in the "Quick Watch" window it does show strItem as an empty string.

PJ on Development: Blog

Strange Bug in VB 2005

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