PRB: Microsoft Excel Not Registered in Running Object Table

• Microsoft Visual FoxPro for Windows, versions 3.0 and 3.0b

SYMPTOMS

According to Visual FoxPro Help, the following command will create a reference to a running instance of Microsoft Excel:

   oleApp = GETOBJECT(,"Excel.Application")

   OLE error code 0x800401e3: Operation unavailable

CAUSE

Previous versions of Microsoft Excel register the application object in the OLE RunningObjectTable (ROT) on startup. This would happen under all circumstances, whether Microsoft Excel was Launched using OLE or not.

Microsoft Excel 7.0 does not register the application object in the ROT on startup by default. However, Microsoft Excel 7.0 registers itself in the ROT in any of the following situations:

• When launched by OLE, as in this example:

  CREATEOBJECT("Excel.Application"))

• When a Module is inserted in one of the Workbooks.
• When a WM_USER+18 message is sent to the Main window of Microsoft Excel.

RESOLUTION

In Visual FoxPro, send a WM_USER+18 message to the Main window of Microsoft Excel to force Microsoft Excel to register itself in the ROT.

STATUS

This behavior is by design.

MORE INFORMATION

The following code demonstrates how to create a reference to a running instance of Microsoft Excel 7.0:

   * Start sample code
   * Main program code
   oleExcel = findxl()
   IF TYPE("oleExcel") = "N"
      =MessageBox("No instances of Excel running !")
   ELSE
       oleExcel.WindowState = -4137  &&maximize Excel
   ENDIF

   FUNCTION findxl
   DECLARE LONG FindWindowA IN USER32 AS FindA STRING,STRING
   DECLARE LONG SendMessageA IN USER32 AS SendA LONG, LONG, LONG, LONG

   WM_USER = 1024
   PRIVATE myExcelApp
   PRIVATE mySendMessage

   hwnd = FindA("XLMAIN", 0)
   IF hwnd = 0 then
      RETURN 0
   ELSE
      mySendMessage = SendA(hwnd, WM_USER + 18, 0, 0)
      myExcelApp = GetObject(, "Excel.Application")
      RETURN myExcelApp
   ENDIF

   ARTICLE-ID: Q132535
   TITLE     : Releasing Object Variable Does Not Close Microsoft Excel

   ARTICLE-ID: Q128994
   TITLE     : Behavior of GETOBJECT()With Excel and Word For Windows