Hello @Zhangchangsheng,
RTD packages are developed and tested in C language only. If you select C++, the RTD package will not show up to attach it to the project, however, they are made so that C++ is compatible through the "__cplusplus" macro.
In order to create a C++ application, you will need to create a C application and then convert it through the ""File > New > Convert to a C/C++ Project" option. There are various considerations when doing this, such as modifying the linker file, startup file, and changing bl main function; please refer to the community for some pointers:
Best regards,
Julián
