Exceptions question

[IX]

My knowledge and understanding of c++ exceptions is very poor so please forgive me if this is a stupid question. It probably is.

I want to try to add some kind of simple crash dump to a machine so that when it inevitably goes down in flames, I'll be able to see what led up to the crash. So how can I catch any unhandled exception in the machine dll so I can execute some code when something goes wrong? I can't wrap my machine in a try/catch (or can I?) so is it possible to have a catch-all exception handler or do I have to put try/catch statements absolutely everywhere?
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Toshiba Satellite Pro L300-28W. Intel Core 2 Duo T5870 2GHz, 3GB ram, Windows 7 Home Premium 32 bit.

[oskari]

You can do that but /nocr and a debugger should be easier.

[IX]

[btd]

I'm not convinced that catching exceptions will help you. Correct me if I'm wrong, but the exception generally only tells you what went wrong, not where or why. If you really must debug without a debugger, then OutputDebugString statements will probably be more helpful than try/catch blocks.

If you must wrap everything in try/catch blocks, you shouldn't need too many of them. If your machine crashes, it's probably going to do it in Tick() or Work().

OT: C++ exceptions are abused far more often than they're used properly. This makes me sad. And yes, wrapping code in a big try/catch to catch all exceptions counts as abuse.

[oskari]

Windows catches all exceptions your try/catch would anyway, so what's the point?

[IX]

Please be tolerant, I'm only a drummer

What I'm aiming to do is keep a log of the machine's state so that when one of those elusive bugs pops up and crashes the machine, I'll be able to see not only where it went wrong but more importantly what steps led to the failure. Armed with that information, I'll be able to easily recreate the problem catch it with the debugger.

So the idea is that I'll either output significant information into a file as the machine is running or store it in some kind of buffer. Then when a crash happens, I'll need to close any open file handles or dump the stored info to a file and clean up. I figured that this would probably involve catching exceptions but perhaps I'm wrong. If I was making a standalone executable I'd try putting a try/catch in main() but I don't know how that could be done for a dll, or even whether it's possible.

So in short, all I really want to do is detect when it all turns to shit and save some useful info that will help me reproduce the crash.

@btd: Is the try/catch in main() approach bad? Almost every tutorial I've seen does that.
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Toshiba Satellite Pro L300-28W. Intel Core 2 Duo T5870 2GHz, 3GB ram, Windows 7 Home Premium 32 bit.

[oskari]

This is what buzz does:

[btd]

I'm still not convinced that exception handling is the right tool for this job. If all you're worried about is having an open handle to your log file, just open and close the file each time you write a message to it (although I suspect this is a non-issue anyway, as Windows will close any open handles when buzz.exe exits). Or just use OutputDebugString and DebugView instead.

Also: many of these "hard to reproduce" bugs are caused by multithreading issues, or by writing past the end of a buffer into some other memory location. Neither of which is easy to debug, no matter how much logging you do.

[IX]