如何在C代码中模拟C ++命名空间功能？

I'm developing a software which is in C++ but that communicates with a C app through a shared header file containing the communication protocol. Since C is "more basic" than C++, I always need to write the header in C code (so C++ also gets it); otherwise it wouldn't work for the second app.I'm developing a software which is in C++ but t