Resolved - Need a cancel button

I need a cancel button for a program which goes into this loop searching the entire hard drive. It can be a lengthy process waiting for it to stop on its own. Where do I put the code and what code is best to use?

VB Code:

Private Function SearchForFiles(FP As FILE_PARAMS) As Double
 
  'local working variables
   Dim WFD As WIN32_FIND_DATA
   Dim hFile As Long
   Dim nSize As Long
   Dim sPath As String
   Dim sRoot As String
   Dim sTmp As String
        
   sRoot = QualifyPath(FP.sFileRoot)
   sPath = sRoot & "*.*"
   
  'obtain handle to the first match
   hFile = FindFirstFile(sPath, WFD)
   
  'if valid ...
   If hFile <> INVALID_HANDLE_VALUE Then
   
     'This is where the method obtains the file
     'list and data for the folder passed.
     '
     'GetFileInformation function returns the size,
     'in bytes, of the files found matching the
     'filespec in the passed folder, so it is
     'assigned to nSize. It is not directly assigned
     'to FP.nFileSize because nSize is incremented
     'below if a recursive search was specified.
      nSize = GetFileInformation(FP)
      FP.nFileSize = nSize
 
      Do
      
        'if the returned item is a folder...
         If (WFD.dwFileAttributes And FILE_ATTRIBUTE_DIRECTORY) Then
            
           '..and the Recurse flag was specified
            If FP.bRecurse Then
            
              'remove trailing nulls
               sTmp = TrimNull(WFD.cFileName)
               
              'and if the folder is not the default
              'self and parent folders...
               If sTmp <> "." And sTmp <> ".." Then
               
                 '..then the item is a real folder, which
                 'may contain other sub folders, so assign
                 'the new folder name to FP.sFileRoot and
                 'recursively call this function again with
                 'the ammended information.
                 '
                 'Since nSize is a local variable, whose value
                 'is both set above as well as returned as the
                 'function call value, the nSize needs to be
                 'added to previous calls in order to maintain accuracy.
                 '
                 'However, because the nFileSize member of
                 'FILE_PARAMS is passed back and forth through
                 'the calls, nSize is simply assigned to it
                 'after the recursive call finishes.
                  FP.sFileRoot = sRoot & sTmp
                  nSize = nSize + SearchForFiles(FP)
                  FP.nFileSize = nSize
                  
               End If
               
            End If
            
         End If
         
     'continue looping until FindNextFile returns
     '0 (no more matches)
      Loop While FindNextFile(hFile, WFD)
      
     'close the find handle
      hFile = FindClose(hFile)
   
   End If
   
  'because this routine is recursive, return
  'the size of matching files
   SearchForFiles = nSize
   
End Function

Thanks in advance!

Create a button named cmdCancel (or something like that), add a variable at the top of the form named bCancel. What you need to do is before you start the Do-Loop set bCancel to False, and in the click event of the cancel button set bCancel to True. Also change the Do-Loop to check :

VB Code:

Loop While FindNextFile(hFile, WFD) And bCancel = False

I also added the vbcode tags to your code to make it easier to read.

Excuse my ignorance on this one, I get a 'Variable not defined' error.
If a Function is Private and I Dim a variable in the main form code, then do I have to dim it again in the function?

Thanks for tidying up the code with the tags, I'll do that next time.

You can use also DoEvents

VB Code:

'Declare on general section
Public bCancel As Boolean
 
 
bCancel = False
     
Do
 
 DoEvents
 '....
 If bCancel Then Exit Do
 
Loop While FindNextFile(hFile, WFD)
 
Private Sub cmdCancel_Click()
    bCancel = True
End Sub

Depending on the code happening in the Do...Loop the DoEvents could slow the whole thing down quite a bit, so it might be worth sticking in a counter and only firing DoEvents every nth loop.

as oh1mie stated:

bCancel is declared in the General Declarations section of the form...
unless this function is running in a module.. then u will need to put the bCancel as publice in the mod..

Public bCancel as Boolean

then in the click event of the cance button set the bCancel = True

be sure to set bCancel back to false after its done "canceling"

The code is not in a module, just a private function but I still get the 'Variable not defined' error despite having Dimmed it in the Form Load area

and its highlighting bCancel??

and.. not the form load... u want it in the General Declarations section...
thats ALL the way at the top.. above all other subs..

Left dropdown in the code window will say (General) and the right dropdown will say (Declarations)

Quote:

---

Originally Posted by imperialdata

The code is not in a module, just a private function but I still get the 'Variable not defined' error despite having Dimmed it in the Form Load area

---

If you dim variable on form load section, it works only on the form load prosedure.

Move it to the general section to works in all prosedures on the that form

Thanks for that guys. As someone who comes back to VB after a long time not doing anything, the basics can get a bit rusty.

Tried what you suggested and got 'Invalid outside procedure' error on this code (where I put it in the General Declarations area as you said). The word false was highlighted:

VB Code:

Option Explicit
 
'Cancel button
Dim bCancel As Boolean
 
'Set cancel button to false
bCancel = False

if the variable is in the general declarations section then you should declare it 'Private bCancel As Boolean'.

It looks like you probably have bCancel = False outside of any procedures, but it is unnecessary to set it to false because it defaults to that anyway.

Removing bCancel = false allowed me to get past the error but cancel button has no effect. It seems to have no focus.

Quote:

---

Originally Posted by imperialdata

Removing bCancel = false allowed me to get past the error but cancel button has no effect. It seems to have no focus.

---

Did you forget DoEvents?

Yup, wasn't sure where it went, had it in the wrong part of the code. Cancelling seems fine now but as Bushmobile said, it has slowed the whole thing down. I'm checking for files across large hard drives and searching is very slow.
How would I fire the Do Events every, say, 10th loop?

Quote:

---

Originally Posted by imperialdata

Yup, wasn't sure where it went, had it in the wrong part of the code. Cancelling seems fine now but as Bushmobile said, it has slowed the whole thing down. I'm checking for files across large hard drives and searching is very slow.
How would I fire the Do Events every, say, 10th loop?

---

VB Code:

Dim iCount As Integer
 
Do
 
    iCount = iCount + 1
    If iCount = 10 Then
       DoEvents
       iCount = 0
    End If
 
Loop While FindNextFile(hFile, WFD)

if you have a loop like this with doevents in it, you need to be careful that someone
doesn't close your program while you are running the loop. It will continue to run even though the main form is closed. Since doevents has a return value equal to the number of visible forms, you should change the code to something like this:
'this code will call doevents once for every 10 counts
DIM Cnt as Integer 'place at beginning of sub

'then in your loop (in fact, put this right before the Loop keyword)
Cnt = Cnt + 1
if Cnt = 10 then
cnt = 1
if doevents() = 0 then exit Do ' or exit Loop, depending if you do cleanup routines
' in this case, you still need to close a file, so exit do will do...
end if

I hope this helps... :)

Thanks guys, excellent help.

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Thank you. :)