How to log an c++ exception

Question

Hello!

Do you know how can I log the exception ? right now the message in the catch statement is printed, but i cannot understood why ins´t Manage.Gere() called sussefully .

try{
    Manager.Gere(&par,&Acc, coman, comando, RunComando, log, &parti, comandosS, RunComandosSuper,true);
}
catch (...)
{
    log("ERROR ENTER GERE*****");
}


Perif::Gere(CString *par, CString *Acc, HANDLE coman, HANDLE comando, HANDLE RunComando, Log &log, CString *parti, HANDLE comandosS, HANDLE RunComandosSuper,bool first)
{
    log->LogD("Perif :: Gere Enter****** "); //It doesnt get printed

}

Answer 1

First thing you need there is find which exceptions Manage.Gere can throw.
Then catch them specifically like catch(FirstExceptionGereThrows &exc) and when you catch all possible exceptions, you'll know what is failing in Manage.Gere.

catch(FirstException &exc){
   log << "Failed because FirstException\n";
}catch(SecondException &exc){
   log << "Failed because SecondException\n";
}

After, and if you are lucky enough the exceptions thrown by Manage.Gere may include some extra info about the crash which you could log as well.

catch(FirstException &exc){
   log << "Failed because FirstException: " << exc.what() << "\n";
}

Answer 2

A well-behaved API should only throw objects of types derived from std::exception. If that's the case, then the exception will have a member function const char *what() containing a message, which will hopefully describe the error. So you could try this, and hope that it helps:

try {
    Manage.Gere(...);
} catch (const std::exception &e) {
    log(e.what());
} catch (...) {
    log("Manage.Gere threw unknown exception");
}

If it throws a type that isn't a std::exception, then you will need to look at the documentation and/or source for the function to see what could go wrong, and what types it does throw. If none of this is available, I would be looking for a better library.

Answer 3

As others have suggested, RTFM is really the answer. However, I've found that lazy programmers often write code like:

if ( something ) {
   throw "Something has happened!";
}

so it is always worthwhile trying to catch both const char * ans std::string:

try {
   // stuff
}
catch( const char * s ) {
    cerr << s << endl;
}
catch( const std::string & s ) {
    cerr << s << endl;
}
// other catches here