Using C++ in RIOT

Levels of Support

A CPU in RIOT can have three levels of support for C++ code:

1. No support for C++ at all
2. C++ is supported, but no libstdc++ implementation is available
3. C++ is supported and a libstdc++ implementation is available

The reason for missing or only partial C++ support can be one (or more) of the following:

• No libstdc++ implementation for the target platform is available to RIOT, or the official RIOT docker image is missing it
• Missing toolchain support for a given target platform
• The C++ toolchain requires library code (such as constructor guards for the thread safe initialization of statically allocated instances) or hooks in the startup process to perform initialization

Using C++

In order for C++ code to compile with RIOT, the following needs to be done:

• All C++ files must have the file extension .cpp, all C++ headers .hpp
  • For external code, overwriting the make variable SRCXXEXT e.g. to cxx can be used to compile C++ files with other extensions, e.g. .cxx
• FEATURES_REQUIRED += cpp must be added to the applications Makefile
  • If additionally the libstdc++ is used, FEATURES_REQUIRED += libstdcpp must be set.

RIOT Modules in C++

RIOT modules should be written in C, so that boards/platforms without or partial C++ support can still use these modules. However, external modules, packages and modules that require C++ support anyway (e.g. the Arduino compatibility features) can be written in C++. Also, some modules might be designed as compatibility layer for C++ or provide convenient access to RIOT-OS’ features using C++ APIs. These modules/packages have to depend on the cpp feature (FEATURES_REQUIRED += cpp) and possibly the libstdcpp feature using their Makefile.dep.

See Also

Reference C++ modules for a list of C++ modules.