Creating Exceptions

Notes

• A function, which needs to generate an exception uses the throw command.
• throw
  • If called with a single argument, a new exception of that type is created
  • If called with no argument, a previously caught exception is re-thrown .
  • If called with no argument and no previous thrown exception, the program is terminated.
• When an exception is thrown
  • all executable code in the stack is skipped until a catch occurs
  • Each time a function is exited, any object instances that go out of lifetime have their destructors called.
• If an exception is thrown in a constructor, the class instance is never created.
• If an exception is thrown in a destructor, the program is terminated
• In any case, always free any dynamic memory allocated in a function that will call an exception before the exception is called.
• And use a catch, re-throw to free any dynamic memory in a function that does not handle exceptions.
• See throw.cpp.