Any idea to get a more prowerful try - catch ?

[tonnot]

I have implemented a try catch with

catch (exception & e)
{ Q_debug()<< "Standard exception: "<< e.what()";
}

catch (exception & e)
{ Q_debug()<< "Standard exception: "<< e.what()";
}

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But my program crash and I have not reach the catch line...
(Only I can detect some simple errors, but in example when save a stl::vector with less information that expected, my app simply chrash)
Any idea ?
Is there any more I can write to have more control on errors ?
The errors I want to control are mainly related with c++ code, not on QT objects
Thanks

[wysota]

If something doesn't throw exceptions then don't expect to catch one.

[squidge]

If you don't know what is going to be thrown how can you possibly catch it? The only real solution is the catch all "catch (...)", but of course you'll get no more information in this case and OS errors (such as memory access violations) are normally not caught unless you use OS specific exception catching.

[SixDegrees]

'app simply crash' doesn't provide any meaningful information, and there are many ways for an app to crash that don't involve throwing exceptions.

Run your app in a debugger, or use stdout debugging to examine intermediate variable contents.

[tonnot]

Ok, but then all converst into a simple control of things using if's , isn't.
So, I dont see the convenience of using exceptions control, because it seems that only can deal with some errors, isn't.
What is your opinión about this ? I have seen that is normally to avoid exceptions catching.
And I have not seen any of this into QT examples...
Thanks

[wysota]

Exceptions are not some magical general mechanism for handling errors. Specific code has to be implemented in a way that makes it throw exceptions in particular exceptional situations. Then some other code that uses this code can catch those exceptions and handle them. Qt doesn't throw exceptions itself so there are no examples of using exceptions with Qt.

[squidge]

tonnot, consider the difference:

if (!somefunction()) {
//clean up
return; 
}
if (!someOtherfunction()) {
// clean up
return;
}
// etc.

if (!somefunction()) {
//clean up
return; 
}
if (!someOtherfunction()) {
// clean up
return;
}
// etc.

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with the functions themselves also having cleanup code...

and

try {
somefunction();
someOtherfunction();
} catch (someException &e) {
// cleanup, knowing what went wrong. 
}

try {
somefunction();
someOtherfunction();
} catch (someException &e) {
// cleanup, knowing what went wrong. 
}

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Much nicer.