virtual const char* what() const throw() { }
AFAIK it\'s a function that will return a constant pointer to a mutable char. The rest I am not sure.
Base class for all library exceptions.
This is the base class for all exceptions thrown by the standard library, and by certain language expressions. You are free to derive your own exception classes, or use a different hierarchy, or to throw non-class data (e.g., fundamental types).