Archives containing compiled C++ binaries can execute malicious code immediately upon extraction or run.
It may also be a specific compressed backup of a private C++ project involving Real Aperture Radar (RAR) simulation or signal processing, though such files are rarely found outside of private environments. Safety Warning CppRadar2.rar
If you already have the file, upload it to VirusTotal to check for detections by major antivirus engines. CppRadar2.rar