ListBox question

[Grok]

Given a populated ListBox, I'd like to delete the blank lines.

Code Select Expand

   Dim lRet As Long, lPos As Long
   Dim strSearch As String
   strSearch = ""
   lRet = SendMessage(List1.hwnd, LB_FINDSTRING, -1, ByVal strSearch)
   If lRet = LB_ERR Then Exit Sub
   lPos = lRet
   lRet = SendMessage(List1.hwnd, LB_DELETESTRING, lPos, 0)

However, after LB_FINDSTRING, lRet is always -1, no matter how many blank lines are in the listbox.  If I search for any string with strlen>0, the search succeeds.

What is the correct solution for finding blank lines in a listbox?

[Kp]

Given a populated ListBox, I'd like to delete the blank lines.

Code Select Expand

   Dim lRet As Long, lPos As Long
   Dim strSearch As String
   strSearch = ""
   lRet = SendMessage(List1.hwnd, LB_FINDSTRING, -1, ByVal strSearch)
   If lRet = LB_ERR Then Exit Sub
   lPos = lRet
   lRet = SendMessage(List1.hwnd, LB_DELETESTRING, lPos, 0)

However, after LB_FINDSTRING, lRet is always -1, no matter how many blank lines are in the listbox.  If I search for any string with strlen>0, the search succeeds.

What is the correct solution for finding blank lines in a listbox?

I note that you're doing "ByVal strSearch" in the SendMessage call.  I may be wrong, but that sounds like it would pass the wrong data.  According to LB_FINDSTRING documentation, the last paramater is a pointer to the string for which to search - so maybe ByRef would be more appropriate?

[Camel]

Given a populated ListBox, I'd like to delete the blank lines.

Code Select Expand

   Dim lRet As Long, lPos As Long
   Dim strSearch As String
   strSearch = ""
   lRet = SendMessage(List1.hwnd, LB_FINDSTRING, -1, ByVal strSearch)
   If lRet = LB_ERR Then Exit Sub
   lPos = lRet
   lRet = SendMessage(List1.hwnd, LB_DELETESTRING, lPos, 0)

However, after LB_FINDSTRING, lRet is always -1, no matter how many blank lines are in the listbox.  If I search for any string with strlen>0, the search succeeds.

What is the correct solution for finding blank lines in a listbox?

I note that you're doing "ByVal strSearch" in the SendMessage call.  I may be wrong, but that sounds like it would pass the wrong data.  According to LB_FINDSTRING documentation, the last paramater is a pointer to the string for which to search - so maybe ByRef would be more appropriate?

It depends on how you've declared SendMessage IIRC. If you have the third param declared as "As Any" or "As String", it will be converted to a pointer automaticly. My suggestion is to declare it "As Long" and use the StrPtr([String]) function to get a pointer to your string for clarity's sake.
But to answer your question Grok, I'm pretty sure you just need to change your -1 to 0, because VB isn't zero-based.

[Grok]

But to answer your question Grok, I'm pretty sure you just need to change your -1 to 0, because VB isn't zero-based.

The -1 tells LB_FINDSTRING where to begin the search after.  If I used 0, the search would begin after the first entry.  MSDN on LB_FINDSTRING says to use -1 to begin search with the first element of the ListBox.

Note to Kp:  The same code finds non-blank entries just great.  It is only when I search for an empty string that the search fails to find the targets.

Thanks to both of you but this remains unsolved.

[Zonker]

You could always send a LB_GETTEXTLEN msg for each of the items and see if they return 0

[Adron]

LB_FINDSTRING
An application sends an LB_FINDSTRING message to find the first string in a list box that begins with the specified string.

What string doesn't begin with an empty string? I.e. it doesn't make any sense at all to give it an empty string.

Try LB_FINDSTRINGEXACT instead.