"Access Violation"
This is apparently whats causing my application to crash without warning.

Sorry if this a vague post but I've not got much to go on really. The code compiles with no errors or warnings, and the program works fine for hours on a good day, but at times it will crash almost immediately.

This is an mp3 jukebox app using MSVC++ app wizard. A typical scenario is as follows:

launch program...
File -> Open -> Play -> (program crashes, "access violation")
- relaunch program -
File -> Open -> Play -> (plays tune, playlists load/save, all is ok...)

Usually crashes when opening/playing a song but I cant think why....it doesnt do anything elaborate and works most the time.

So, what is an access violation? And how do you go about finding the problem....
is there something that often causes this?

Does MSVC++ have any tools to help find the problem? (Pressing debug when it crashes gives a VERY long list of asm add instructions, nothing helpful (to me at least)).

Sorry if this is too general a question but I've not had this problem before.

Thanks for you're time.

Well, this means you are a very good programmer (it happened to me )


Well, you usually get this when you try to use some resurses you "don't have" (like memory).
Unfortunately, this also occurs because of some bugs in VC6 - try installing the most recent Service Pack (whichever that would be) if you hadn't already done so.

For example, _sometimes_ when you open a Visual C++ generated makefile, you get this error (sometimes it works just fine!) - Microsoft has confirmed this to be a bug, and fixed it in .NET

Also, I would recomend using asserts in your code, especially when using pointers, arrays, and other resurses (like sound files!) .
It is possible you "sometimes" try to use memory past the one allocated ...

If you use malloc it allocates a few bytes before and after (I think!) the buffer it assignes to your program. If you write over those bytes, the data structures of malloc get corrupted and the next time you call malloc it fails and generates a Segmentation Fault (Access Violation).

Well, you didn't give much to go on ... so I can't really give you anything helpfull... sorry

Hope you fix this sucker

Luci

A response! I thought this forum was dead, along with some others I tried.....

Well, there has been a lot of responses to this on codeguru.com, see http://www.codeguru.com/forum/showthread.php?t=304102&page=3 if you're interested.

I've pretty much given up on this.....the amount of help I've had and time I've put in to getting this one problem fixed is getting beyond a joke. But if anyones got any pearls of wisdom just waiting to be shared about access violations (I'm not writing past an array, believe me - its been checked by others too) the code is posted on this site, along with about 30 responses - but its still doing exactly the same thing. Aaaaarrrhhhhh!

Its a shame cus I've now pretty much wasted a month but there you go......

I've read (most) of the replyes you got there - they make perfect sense, I'm sorry they didn't solve your problem....
Unfortunatelly, I don't really have much time right now (I'm at work ), but I see your problem is with CString; I have some (bad ) experience with MFC and CString : see http://support.microsoft.com/default...b;EN-US;193100 for some reference....
I don't see any deletes in your code, so this probably isn't the problem, but...
Anyway, I promise to look on your code some other time, and if I get a brainstorm, I'll let you know....

Offtopic: I just thought this was kind of funny:



Hope you don't mind, you are probably pretty depressed right now...

P.S: Try posting here http://forum.softpedia.com/forumdisplay.php?forumid=73

It's a romanian site, but you can post in English; the guys are pretty good (they helped me), but you'll probably need to register first (it's free).

Link to off topic messages.