Q153463: HOWTO: Close Applications from Visual Basic

Article: Q153463
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:4.0
Operating System(s): 
Keyword(s): kbVBp400
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Standard Edition for Windows, version 4.0 
- Microsoft Visual Basic Professional Edition for Windows, version 4.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 4.0 
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SUMMARY
=======

Periodically it may be necessary for a programmer to close down another
application from Visual Basic code. For example, your application might conflict
with some other known utility, so you need to close the conflicting utility so
your application can work correctly. The step-by- step example in this article
shows how to do it using the Windows API.

MORE INFORMATION
================

Step-by-Step Example
--------------------

1. Start a new Visual Basic project. Form1 is created by default.

2. Add a command button (Command1) to Form1.

3. Add the following code to the General Declarations section of Form1:

     Option Explicit

     Private Declare Function FindWindow Lib "User" (ByVal lpClassName _
        As Any, ByVal lpWindowName As Any) As Integer
     Private Declare Function PostMessage Lib "User" (ByVal hWnd _
        As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, _
        lParam As Any) As Integer

     Private Const WM_QUIT = &H12

     Private Sub Command1_Click()
       Dim sTitle As String
       Dim iHwnd As Integer
       Dim ihTask As Integer
       Dim iReturn As Integer
       sTitle = "Notepad - (Untitled)"
       iHwnd = FindWindow(0&, sTitle)
       iReturn = PostMessage(iHwnd, WM_QUIT, 0, 0&)
       MsgBox "Notepad has been Closed Down"
     End Sub

4. Start Notepad by double-clicking the Notepad Icon.

5. Activate Visual Basic, and press F5 to start the project. Click the command
  button and the instance of Notepad you started should automatically close
  down. The message box will confirm this.

NOTE: For Visual Basic for Windows, 32-bit only, version 4.0 and Visual Basic for
Windows version 5.0, you need to use the following code:

1. Start a new Visual Basic project. Form1 is created by default.

2. Add a command button (Command1) to Form1.

3. Add the following code to the General Declarations section of Form1:

     Option Explicit

     Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal
       lpClassName As Any, ByVal lpWindowName As Any) As Long
     Private Declare Function PostMessage Lib "user32" Alias "PostMessageA"
       (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, ByVal lParam
       As Long) As Long
     Private Const WM_QUIT = &H12
     Private Sub Command1_Click()
      Dim sTitle As String
       Dim iHwnd As Long
       Dim ihTask As Long
       Dim iReturn As Long
       sTitle = "Untitled - Notepad"
       iHwnd = FindWindow(0&, sTitle)
       iReturn = PostMessage(iHwnd, WM_QUIT, 0&, 0&)
       MsgBox "Notepad has been Closed Down"
    End Sub

4. Start Notepad by double-clicking the Notepad Icon.

5. Activate Visual Basic, and press the F5 key to start the project. the command
  button and the instance of Notepad you started should automatically close
  down. The message box will confirm this.


Additional query words:

======================================================================
Keywords          : kbVBp400 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB400Search kbVB400
Version           : WINDOWS:4.0
Issue type        : kbhowto

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