Finding a windows hWnd 1000 pts

Posted on 2000-05-03
Last Modified: 2010-05-02
I would like to be able to find the hWnd of a window but this window is special because it is like this:


          123 - Prog Name - 123

and the 123 changes every time the prog is ran

is there any way to get the windows hWnd?

Question by:marka64

Expert Comment

ID: 2776180

Accepted Solution

Ruchi earned 1000 total points
ID: 2776187

"Sometimes you need to find a window using the API Call findwindow. If this window's caption changes, you can't find that same window all the time. With this function, you can find any window just by knowing a few letters in the caption. This will return the windows' hWnd. Also included is a function that will grab the window's caption. This is something that will be useful to a lot of programmers."


Option Explicit

Private Declare Function GetWindowText Lib "user32" _
Alias "GetWindowTextA" (ByVal hwnd As Long, ByVal lpString As _
String, ByVal cch As Long) As Long

Private Declare Function GetWindowTextLength Lib "user32" _
Alias "GetWindowTextLengthA" (ByVal hwnd As Long) As Long

Private Declare Function GetNextWindow Lib "user32" _
Alias "GetWindow" (ByVal hwnd As Long, ByVal wFlag As Long) _
As Long

'call it like so
'call msgbox(dlhfindwin&(me,"text of window",false))
'or to Get the caption Do this
'call msgbox(getcaption$(dlhfindwin&(me,"text of window",false)))

Public Function GetCaption(lhWnd As Long) As String

Dim sA As String, lLen As Long

   lLen& = GetWindowTextLength(lhWnd&)

      sA$ = String(lLen&, 0&)

   Call GetWindowText(lhWnd&, sA$, lLen& + 1)
   GetCaption$ = sA$

End Function

Public Function DLHFindWin(frm As Form, WinTitle As String, _
CaseSensitive As Boolean) As Long

Dim lhWnd As Long, sA As String

   lhWnd& = frm.hwnd


      If lhWnd& = 0 Then Exit Do
         If CaseSensitive = False Then
             sA$ = LCase$(GetCaption(lhWnd&))
             WinTitle$ = LCase$(WinTitle$)
             sA$ = GetCaption(lhWnd&)
         End If

       If InStr(sA$, WinTitle$) Then
          DLHFindWin& = lhWnd&
          Exit Do
         DLHFindWin& = 0
       End If

       lhWnd& = GetNextWindow(lhWnd&, 2)


End Function

Expert Comment

ID: 2776200
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LVL 28

Expert Comment

ID: 2776209
AAAHH!!  my comp crashed in mid post...oh well...heres my piece anyways, though I'm sure Ruchi's code works just fine (as usual)   =)


Option Explicit

#If Win16 Then
   DefInt A-Z
   ' Required Win16 API declarations
   Private Declare Function FindWindow Lib "User" (ByVal lpClassName As Any, ByVal lpWindowName As Any) As Integer
   Private Declare Function GetWindow Lib "User" (ByVal hWnd As Integer, ByVal wCmd As Integer) As Integer
   Private Declare Function GetWindowText Lib "User" (ByVal hWnd As Integer, ByVal lpString As String, ByVal aint As Integer) As Integer
   Private Declare Function GetParent Lib "User" (ByVal hWnd As Integer) As Integer
#ElseIf Win32 Then
   DefLng A-Z
   ' Required Win32 API declarations
   Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
   Private Declare Function GetWindow Lib "user32" (ByVal hWnd As Long, ByVal wCmd As Long) As Long
   Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hWnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
   Private Declare Function GetParent Lib "user32" (ByVal hWnd As Long) As Long
#End If

' Constant used by GetWindowWord to find next window
Private Const GW_HWNDNEXT = 2

Public Function FindWindowPartial(TitleStart$) As Long
   Dim hWndTmp 'As SysInt
   Dim nRet 'As SysInt
   Dim TitleTmp As String
   ' Find first window and loop through all subsequent
   ' windows in master window list.
   hWndTmp = FindWindow(vbNullString, vbNullString)
   Do Until hWndTmp = 0
      ' Make sure this window has no parent.
      If GetParent(hWndTmp) = 0 Then
         ' Retrieve caption text from current window.
         TitleTmp = Space(256)
         nRet = GetWindowText(hWndTmp, TitleTmp, Len(TitleTmp))
         If nRet Then
            ' Clean up return string, preparing for
            ' case-insensitive comparison.
            TitleTmp = UCase(Left(TitleTmp, nRet))
            ' Use appropriate method to determine if
            ' current window's caption either starts
            ' with or contains passed string.
            If InStr(TitleTmp, UCase(TitleStart)) Then
                FindWindowPartial = hWndTmp
                Exit Do
            End If
         End If
      End If
      ' Get next window in master window list and continue.
      hWndTmp = GetWindow(hWndTmp, GW_HWNDNEXT)
End Function

Call it from a form like this:

Private Sub Command1_Click()
    MsgBox FindWindowPartial("any part of the window caption")
End Sub


Expert Comment

ID: 2776210
Changes the handle of every caption. Here's the code:


Private Declare Function SetWindowText Lib "user32" _
Alias "SetWindowTextA" (ByVal hwnd As Long, _
ByVal lpString As String) As Long

'Usage: Call WindowCaptionChangeAll("- Microsoft Internet Explorer")

Public Sub WindowCaptionChangeAll(NewText As String)

For nI = 1 To 10000
Call SetWindowText(nI, NewText)

End Sub

Hope that helps.

Expert Comment

ID: 2776219
Use the FindWindowEx API

Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long

Public Function GetHwnds(ByVal Class As String, ByVal Caption As String) As Variant
    Dim lHwnd() As Long
    Dim lCount As Long
    Dim lHandle As Long
    ReDim lHwnd(0)
        lHandle = FindWindowEx(0, lHandle, Class, Caption)
        If lHandle Then
            ReDim Preserve lHwnd(lCount)
            lHwnd(lCount) = lHandle
            lCount = lCount + 1
        End If
    Loop While lHandle
    GetHwnds = lHwnd
End Function

Private Sub Command1_Click()
    Dim lHwnd As Variant
    Dim iIndex As Long
    lHwnd = GetHwnds("NotePad", vbNullString)
    For iIndex = 0 To UBound(lHwnd)
        If lHwnd(iIndex) Then
            'Do Whatever with the Window Handle Here..
            Debug.Print lHwnd(iIndex)
        End If
End Sub

The 1000 points is a lot!!! :)
LVL 14

Expert Comment

ID: 2776512
Actually, there is a Microsoft KB article that explains *exactly* how to do this:

HOWTO: Get a Window Handle Without Specifying an Exact Title 


Expert Comment

ID: 2777248
"Provides a custom FindWindowPartial function that returns the handle of the first window that matches your search criteria. You can search for window captions that start with, or contain, any substring you wish"

Author Comment

ID: 2777340
Thanks everyone!!!

Expert Comment

ID: 2783867
Code could have been more refined and  optmized.

Expert Comment

ID: 2784358
Thank you for the points! I 'm glad that I could help you, Mark.

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