How To Close Applications from Visual Basic

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Article ID: 153463 - View products that this article applies to.
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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.

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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.

Properties

Article ID: 153463 - Last Review: June 29, 2004 - Revision: 4.1
APPLIES TO
  • Microsoft Visual Basic 4.0 Standard Edition
  • Microsoft Visual Basic 4.0 Professional Edition
  • Microsoft Visual Basic 4.0 Enterprise Edition
Keywords: 
kbhowto KB153463

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