HOWTO: Get the HRESULT From a COM Object
ID: Q186298
|
The information in this article applies to:
-
Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b, 5.0, 5.0a
SUMMARY
When you make calls to a function of a COM interface, the function returns
an integer return code, or HRESULT. This value consists of a severity code,
context information, a facility code, and a status code that describes the
result. In Visual FoxPro, it may be useful to obtain the HRESULT for
debugging purposes or error handling.
MORE INFORMATION
In Visual FoxPro, it is not possible to obtain the HRESULT directly.
However, when an OLE error occurs (error number 1426), the HRESULT is in
the text of the error message in the form 0x800nnnnn. The sample code below
demonstrates how to extract the HRESULT from the error message text and
display it in both base 10 and hexadecimal format.
Sample Code
Create a program file named Hresult.prg, with the following code:
*-- Code begins here.
ON ERROR DO getresult IN hresult WITH ;
ERROR(), MESSAGE()
*-- Create an instance of Microsoft Word.
oWord = CREATEOBJECT("Word.Application")
*-- Call an invalid function to test our error handling.
oWord.RaiseError
PROCEDURE getresult
PARAMETER liError, lsMessage
IF liError <> 1426 && Not an OLE error code
*-- Since this error handler now handles all errors, it
*-- would be best to include some more robust error
*-- handling here to handle errors other than #1426.
RETURN
ENDIF
*-- Take the message string and parse the hexadecimal HRESULT.
*-- The VAL() function will do the conversion to a base 10 integer.
liHresult = VAL(SUBSTR(lsMessage, AT("0x", lsMessage), 10))
*-- Display the result in decimal and hexadecimal format.
*-- This section would be used to process the HRESULT as needed,
*-- either by parsing the returned code or otherwise overriding the
*-- default Visual FoxPro behavior.
MESSAGEBOX("OLE function returned HRESULT: " +;
CHR(10) + CHR(13) + ;
STR(liHresult) + " (decimal) " +;
CHR(10) + CHR(13) + ;
TRANSFORM(liHresult, "@0") + " (hexadecimal)", 0, "OLE Error")
RETURN
*-- Code ends here.
REFERENCES
MSDN Library
(c) Microsoft Corporation 1998, All Rights Reserved. Contributions by Mike
Stewart, Microsoft Corporation
Additional query words:
kbDSupport kbDSE beta99 FxinteropOcx FxinteropOle FxprgGeneral vfoxwin
Keywords :
Version : WINDOWS:3.0,3.0b,5.0,5.0a
Platform : WINDOWS
Issue type : kbhowto