c++: strange syntax in what() method of std::exception

Question

When i am inheriting from std::exception in order to define my own exception type, i need to override the what() method, which has the following signature:

virtual const char* what() const throw();

This definitely looks strange to me, like if there were two method names in the signature. Is this some very specific syntax, like with pure virtual methods, e.g.:

virtual int method() const = 0;

or is this a feature, that could somehow be used in another context, too? And if so, for what could it be used?

Answer 1

virtual const char* what() const throw();

what() is a virtual constant method that returns pointer to const char and must not throw any exception. Not very strange method declaration :)

Answer 2

It is called exception specifications. The throw() doesn't allow any exception to be thrown from inside this method throw(int) would only allow exceptions of type int to be thrown.

Exception specifications will be dropped in C++0x. This gives a very good explanation of the reasons.