VB6-Application Error when I end the program in Debug Mode

Posted on 2003-02-27
Medium Priority
Last Modified: 2008-03-03

   I am writing a program using several API calls, but I found that VB6 will have application error when I forced to end the program under debug mode.

Here are the error message :
VB6.exe - Application Error
The instruction at "0x0fa95681" referenced memory at "0x00ffff00", The memory could not be "read".

  Personally, I found that it is caused by the "incomplete" calls of windows API, so how can I solve this problem, as it will lose all the changes of codes after error.

Thomas Cheung

Question by:thomascy
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Expert Comment

ID: 8038862
I've run into this problem as well. You have to be very careful when programming with API calls in VB. I don't think there is any way around it other then saving your work before you do a test run...

You could also compile the code before running it, that way it won't crash VB if the program dies.

Hope that helps.

Expert Comment

ID: 8039836
Go to Tools>Options there is a option to set VB to automatically save your project each time you run it.   This way you don't lose your changes if the IDE crashes with the program.

Expert Comment

ID: 8040175
I've run into this problem only when i change the WindowProc for a form using API.In this case the sollution was to change the WindowsProc back to the default, before close the program.How kind of API call do you have in your program?>
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Expert Comment

ID: 8040988
you could add an Errorhandler to your code;

at the begining of each sub/function add:

On Error Goto errhdlr

at the end of each sub/function add:

Stop       'So you know what sub/function caused the error
(Call your cleanup routine here)

If you want to do a hard stop, creat an error in the next line of code to be executed. Then Step through your cleanup routine.

If there is a hard error(ie. code execution stops in a sub/function without calling the errorhandler), comment that line out.


Accepted Solution

Da_Weasel earned 300 total points
ID: 8042465
the problem with API (hard errors) is that VB Error handling doesn really work, or at least not in a reliable fashion.
Like catalin tata said, you have to watch your WinProc's...and carfully code anything that makes use of APIs.

Handling errors work a little different with API than VB code.
In VB you add a "On Error" statement and then wait for an error to happen, see what the error was, and handle it.
When using API you have to do your error handling (error prevetion is a better name) before calling them.  Verify all data that is being passed to them.  If the data being passed is coming from an unknown source then you should setup a test program that loops through all of the possible and even a few near impossible senarios, then write code to check and handle all of these situations.

Expert Comment

ID: 8901002
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