Shall I use cerr

Question

Is it in good style do use cerr in situation described below?

try
    {
    cout << a + b;
    }
    catch(const IntException& e)
    {
        cerr << "Exception caught: " << typeid(e).name(); //using cerr not cout
    }
    catch(...)
    {
        cerr << "Unknown exception.";//using cerr not cout
    }

or cout should be used? See comments in code.

Answer 1

stderr is the traditional stream to send error messages (so that the OS/shell/whatever can capture error messages separately from "normal" output), so yes, use std::cerr!

I make no comment as to whether catching an exception simply to print it out is any better than simply letting the exception propagating out of your application...

Answer 2

Yes, because while by default they both go to the terminal, you could change where their output is directed, and you may wish cerr to go to a log file while cout continues to just go to stdout.

Essentially it gives you more control over where different output goes if you want it now or in the future.