WD2000: How to Call the ShellExecute Windows API Function

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SUMMARY

You can call the ShellExecute() Windows API function from a Visual Basic for Applications macro to start another program under Microsoft Windows. Use ShellExecute() instead of Shell (a Visual Basic statement) or WinExec() (a Windows API function) to work around the following limitation of the latter commands:

With Shell and WinExec(), you cannot start an application by specifying a file name only. For example, the following Shell statement will fail:
x = Shell("C:\My Documents\Book1.Xls")
				

MORE INFORMATION

Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements. Below is a sample Visual Basic for Applications macro that calls the ShellExecute() Windows API function. ShellExecute() determines whether Microsoft Excel is already running; if so, it loads Book1.xls into the current Microsoft Excel session. If Microsoft Excel is not already running, ShellExecute() starts Microsoft Excel and loads Book1.xls.
Declare Function ShellExecute Lib "shell32.dll" Alias _
   "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation _
   As String, ByVal lpFile As String, ByVal lpParameters _
   As String, ByVal lpDirectory As String, ByVal nShowCmd _
   As Long) As Long

Declare Function apiFindWindow Lib "User32" Alias "FindWindowA" _
   (ByVal lpclassname As Any, ByVal lpCaption As Any) As Long

Global Const SW_SHOWNORMAL = 1

Sub ShellExecuteExample()
   Dim hwnd
   Dim StartDoc
   hwnd = apiFindWindow("OPUSAPP", "0")

   StartDoc = ShellExecute(hwnd, "open", "C:\My Documents\Book1.xls", "", _
      "C:\", SW_SHOWNORMAL)
End Sub
				
The ShellExecute() function opens or prints the specified file. The following is information about ShellExecute() from pages 901-904 of the Microsoft Windows Software Development Kit (SDK) "Programmer's Reference, Volume 2:Functions."

Parameters

Parameter            Description
---------------------------------------------------------------------------

   hwnd                 Identifies the parent window.

   lpszOp               A string specifying the operation to perform. This
                        string can be "open" or "print".

   lpszFile             Points to a string specifying the file to open.

   lpszParams           Points to a string specifying parameters passed to
                        the application when the lpszFile parameter
                        specifies an executable file. If lpszFile points to
                        a string specifying a document file, this parameter
                        is NULL.

   lpszDir              Points to a string specifying the default
                        directory.

   fsShowCmd            Specifies whether the application window is to be
                        shown when the application is opened. This
                        parameter can be one of the following values:

      Value          Meaning
      ---------------------------------------------------------------------

      0              Hides the window and passes activation to another
                     window.

      1              Activates and displays a window. If the window is
                     minimized or maximized, Windows restores it to its
                     original size and position (same as 9).

      2              Activates a window and displays it as an icon.

      3              Activates a window and displays it as a maximized
                     window.

      4              Displays a window in its most recent size and
                     position. The window that is currently active remains
                     active.

      5              Activates a window and displays it in its current
                     size and position.

      6              Minimizes the specified window and activates the
                     top-level window in the system's list.

      7              Displays a window as an icon. The window that is
                     currently active remains active.

      8              Displays a window in its current state. The window
                     that is currently active remains active.

      9              Activates and displays a window. If the window is
                     minimized or maximized, Windows restores it to its
                     original size and position (same as 1).
				

Returns

The return value is the instance handle of the application that was opened or printed, if the function is successful. (This handle could also be the handle of a DDE server application.) A return value less than or equal to 32 specifies an error.

Errors

The ShellExecute() function returns the value 31 if there is no association for the specified file type or if there is no association for the specified action within the file type. The other possible error values are as follows:
Value          Meaning
---------------------------------------------------------------------------

   0             System was out of memory, executable file was corrupt, or
                 relocations were invalid.

   2             File was not found.

   3             Path was not found.

   5             Attempt was made to dynamically link to a task, or there
                 was a sharing or network-protection error.

   6             Library required separate data segments for each task.

   8             There was insufficient memory to start the application.

  10             Windows version was incorrect.

  11             Executable file was invalid. Either it was not a Windows
                 application, or there was an error in the .exe image.

  12             Application was designed for a different operating system.

  13             Application was designed for MS-DOS 4.0.

  14             Type of executable file was unknown.

  15             Attempt was made to load a real-mode application
                (developed for an earlier version of Windows).

  16             Attempt was made to load a second instance of an
                 executable file containing multiple data segments that
                 were not marked read-only.

  19             Attempt was made to load a compressed executable file. The
                 file must be decompressed before it can be loaded.

  20             Dynamic-link library (DLL) file was invalid. One of the
                 DLLs required to run this application was corrupt.

  21             Application requires Microsoft Windows 32-bit extensions.
				

Comments

The file specified by the lpszFile parameter can be a document file or an executable file. If it is a document file, this function opens or prints it, depending on the value of the lpszOp parameter. If it is an executable file, this function opens it, even if the string "print" is pointed to by lpszOp.

REFERENCES

For more information about how to use the sample code in this article, click the article number below to view the article in the Microsoft Knowledge Base:
212536 OFF2000: How to Run Sample Code from Knowledge Base Articles
For more information about getting help with Visual Basic for Applications, please see the following Microsoft Knowledge Base article:
226118 OFF2000: Programming Resources for Visual Basic for Applications


Microsoft Windows SDK "Programmer's Reference, Volume 2: Functions," pages 901-904

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Article ID: 238245 - Last Review: October 11, 2006 - Revision: 3.2
APPLIES TO
  • Microsoft Word 2000 Standard Edition
Keywords: 
kbhowto kbprogramming KB238245

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