These classes provide support for debugging dynamic memory allocation and for passing exception information from the function where the exception is thrown to the function where it's caught.
Use classes CDumpContext and CMemoryState during development to assist with debugging, as described in MFC Debugging Support. Use CRuntimeClass to determine the class of any object at run time, as described in the article CObject Class: Accessing Run-Time Class Information. Both articles are in Visual C++ Programmer's Guide. The framework uses CRuntimeClass to create objects of a particular class dynamically.