Abstract: After compiling a source file by C++ compiler， the class definition information isn’t remained in object file. Therefore, the program at runtime can’t acquire the class information, such as class name，class hierarchy and so on, and consequently many operations such as dynamic_cast, persistence are impossible to be completed. RTTI is the key to conquer this problem. Although a great deal of importance is attached to RTTI, many C++ programmers are still confused by RTTI realization. In this paper, a concrete RTTI is realized, and it gives C++ programmers a chance to have a glimpse of RTTI realization. 

Key words: RTTI, dynamic_cast, persistence