Due to the macro identifiers limitations which states that an a+ is insignificant and hence, ‘C++’ is not possible. C PreProcessor is the value which is represented by CPP.
However, various variables can be classified and elaborated on in a GNU Make File such as CPPFLAGS which is used in the C++ language stating additional flags for the C preprocessor. Another variable used is the CFLAGS variable which denotes the additional flags used for the C Compiler. The variables of CPPFLAGS and CFLAGS will be used for a given C project. The next variables include CXXFLAGS and CPPFLAGS which denote the additional flags for the compiler of C++.