/GR (Enable Run-Time Type Information)
| Overview | How Do I | Compiler Options
The Enable Run-Time Type Information option (/GR) causes the compiler to add code to check object types at run time. When this option is specified, the compiler defines the _CPPRTTI preprocessor macro. The option is cleared (/GR–) by default.
To find this option in the development environment, click Settings on the Project menu. Then click the C/C++ tab, and click C**++ Language** in the Category box.
For more information on run-time type checking, see in the C++ Language Reference.