Most microcontrollers have good C++ compilers now.
Most C idioms can be written in C++.
Templates, function overloading, and structure member functions allow one to write modular, readable code without classes.
Interfacing to other libraries can be done with extern "C".
Much high-level software (image processing, ROS, etc) is written in C++.
If you pick one systems language for robotics work, pick C++.
If you are working close to the metal, you must learn and understand what C++ is doing behind the scenes.
The only advantage C has is that there's lots of legacy code using C, especially OS code, and occasionally there is obscure or old hardware without a C++ compiler.