Re: C++ exception error messages

An awkward situation with exception handling occurred to me this
morning.
I frequently see (and I'll admit to writing it myself sometimes)
error detection code which does something along these lines:

 if(badness) {
    std::ostringstream err;
    err << "Badness " << errcode << " has occurred while frobbing"
        << " nitzes. blah blah blah";
    throw SomeException(err.str().c_str());
 }

or just using snprintf:

 if(badness) {
    char errc[1024];
    snprintf(errc, 1024, "badness %d occurred ...", errcode);
    throw SomeException(errc);
 }

Yet, of course, by the time we get to a:

 catch(const SomeException& se) { ... }

clause somewhere up the call stack, the above stack has unwound. In
the first case, the std::string from err.str() has had its
destructor run, so our saved pointer is bogus; in the latter,
there's no destructor for char* of course but the 'errc' array is
"gone".