How to catch details of exception

Question

Hi

I have a code snippet where generic catch catch(...) is there. It is not giving me details and I don't know root cause also of exception.

How to identify the error details?

https://code.sololearn.com/cDmeRm6ieL50

In above code, I just have below and it works ok
catch (...)
{
cout << "generic exception\n";
}

but not getting what it throws. So added catch(exception& ex) but it is not handling at all. Removing generic block of exception and only keeping exception& one results into crash.

Please suggest to get details of exception. I am on Visual Studio 2019 on windows environment.

Thanks in advance!!!

Answer 1

The reason this is happening is because you dont throw an exception. To catch the exception you would have to throw an object inherited from std::exception

Answer 2

You can do catch(std::exception& e) and inside the catch block do std::cout << e.what();

Answer 3

type of the argument passed by the throw expression is checked against catch parameters, and only in the case they match, the exception is caught by that handler.

try
{
throw "2";
//throw 2;
}
catch(const char *c){
cout << c <<endl;
}

try{
throw exception();
}
catch (exception& ex)
{
cout << "exception\n" << ex.what();
}

Answer 4

Thanks SimZooo and Jayakrishna🇮🇳

Got it now.....

I have actually an exception caught by catch(...) and no other cacth blocks are there.....

That exception might have occured in any functions out of 100s of functions.... Can i get any info like where and what happened ? Unfortunately I dont check call stack on debug mode as it is running on different machine not having Visual Studio installed

Answer 5

There's not much you can do unless you use a debugger such as the one in visual studio

Answer 6

Not unless you add that informatin to the constructor of the exception

Answer 7

You can use like this :

try
{

throw runtime_error("error at line no: "+to_string(__LINE__) +"\nin file : " __FILE__);

}

catch(exception& ex)
{
cout << ex.what();
}

Answer 8

The block you have memtioned is already there in code snippet shared in question but it is not caught in that code block

Answer 9

Ketan Lalcheta
You can create an exception with a custom string, such as std::exception("{Error message} in file: " __FILE__ " at line:" __LINE__). When the exception is read with e.what(), it will output something like "Index out of bounds in file: main.cpp at line: 255.

Answer 10

I don't have knowledge from where it is thrown

There is huge code base and may have 100 cpp files and from that files , one function might be throwing this exception...

Reason I am going into this matter is to identify the location where exception occurs

Answer 11

I thought I can dump some information of the exception into text or some file as it is not replicated on system having debugger