Question

I am trying to use the following code to test “set_unexpected()”. I expect the code will generate an output like:

In function f(), throw const char* object
Call to my_unexpected
Exception in main(): Exception thrown from my_unexpected

But I got a run-time error: “This application has requested the Runtime to terminate it in an unusual way.” So, what would be the problem? Thanks

struct E {
  const char* message;
  E(const char* arg) : message(arg) { }
};

void my_unexpected() {
  cout << "Call to my_unexpected" << endl;
  throw E("Exception thrown from my_unexpected");
}

void f() throw(E) {
  cout << "In function f(), throw const char* object" << endl;
  throw("Exception, type const char*, thrown from f()");
}


int _tmain(int argc, _TCHAR* argv[])
{
      set_unexpected(my_unexpected);
  try {
    f();
  }
  catch (E& e) {
    cout << "Exception in main(): " << e.message << endl;
  }
    return 0;

}

Answer 1

Visual C++ does not implement correctly exception specifications. As stated here,

Visual C++ departs from the ANSI Standard in its implementation of exception specifications.

and in particular

throw(type) – The function can throw an exception of type type. However, in Visual C++ .NET, this is interpreted as throw(...).

Also here:

Function exception specifiers other than throw() are parsed but not used.

Because of this, your terminate handler is never called, and since no handlers for const char * are present in your code the exception is not caught and the application terminates abnormally.

---

Anyway, keep in mind that exception specifications different from throw() are generally considered a bad idea, and actually the new C++ standard (C++11) deprecates them, introducing noexcept for what throw() was used.