How To Check For a Running Instance of Word 95 From VB

MORE INFORMATION

The recommended method for checking for an instance of a Microsoft Office application is to execute GetObject and trap for error 429, which will be returned if there is no running instance. Because Microsoft Word 95 has no application object, this approach fails and the error 429 will always be returned.

However, because Microsoft Word, exclusively, always begins its title bar text with the "Microsoft Word" sub-string, the GetWindowText API function can be applied to each running window to detect the presence of Microsoft Word 95. The following code demonstrates this procedure and works whether or not Microsoft Word is visible or has a document open. This technique can also be applied to any application that uses a top-level window that starts its title bar text with a known sub-string. The call syntax is demonstrated below:

   boolVariable = GetWordWindow(strTitleStart, hwnd)
				

where:

• boolVariable is set to true for success and false for failure (no window found).

• GetWordWindow is the Visual Basic function that wraps the API function GetWindowText.
• strTitleStart is the sub-string sought. If the title of any top level window begins with this sub-string, the handle of the first such instance will be returned. An empty string will be converted by the function to "Microsoft Word." The function is not case-sensitive.
• hwnd is the window handle. The handle of the last top-level window is returned in case of failure.

Step-by-Step Example

The project in this example runs as a form containing no controls. Clicking on the form itself results in the display of a message box either stating, "I did not find MS Word," indicating that Microsoft Word is not running, or "I found MS Word and its handle is," and displaying the window handle. This example works for all versions of Word for Windows:

1. Open a new Project. Form1 is created by default.
2. From the Project menu (Insert menu in Visual Basic 4), insert a new Module (Module1).
3. Copy the Form Code below to the General Declarations section of Form1.
4. Copy the Module Code below to the General Declarations section of Module1. Be sure each API Declare Function statement is entered on a separate line (line-continuation underscore not allowed by Visual Basic).
5. Take care to remove a duplicate entry of the 'Option Explicit' line for the case when your Tools/Option/Environment/Require Variable Declaration CheckBox has been selected.

       'FORM CODE     ***********************************************
   
       Option Explicit
       Private Sub Form_Click()
       Dim hwnd As Long
           Select Case getWordWindow("", hwnd) 'call getWordWindow
           Case True       'Word is running . . .
               MsgBox "I found MS Word and its handle is " & CStr(hwnd) & "."
           Case Else       'Word is not running
               MsgBox "I did not find MS Word."
           End Select
       End Sub
   
       'MODULE CODE   ***********************************************
   
       Option Explicit
   
       Option Compare Text
   
       Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" _
          (ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) _
          As Long
       Declare Function GetWindow Lib "user32" (ByVal hwnd As Long, _
          ByVal wCmd As Long) As Long
       Declare Function GetTopWindow Lib "user32" (ByVal hwnd As Long) _
          As Long
   
       Public Const GW_HWNDNEXT = 2
   
       Function getWordWindow(appTitle As String, appHandle As Long) _
          As Boolean
       Dim dummyVariable As Long
       Dim lenTitle As Integer
       Dim winTitle As String * 256
   
           'initialize the function return as False
           getWordWindow = 0
           If appTitle = "" Then appTitle = "Microsoft Word"
           lenTitle = Len(appTitle)
   
           'Get the handle of the first child of the desktop window
           appHandle = GetTopWindow(0)
   
           'Loop through all top-level windows and search for the sub-string
           'in the Window title
           Do Until appHandle = 0
               dummyVariable = GetWindowText(appHandle, winTitle, 255)
               If Left(winTitle, lenTitle) = appTitle Then
                   getWordWindow = -1
                   Exit Function
               Else
                   appHandle = GetWindow(appHandle, GW_HWNDNEXT)
               End If
           Loop
       End Function