Question

I need to include some headers originally written in C in a C++ project. In the header files, the restrict keyword is used, which leads to a syntax error for C++.

I am looking for a preprocessor macro which checks whether I am compiling with a C++ compiler and removes the restrict keyword in this case.

Answer 1

#ifdef __cplusplus
#define restrict
#endif

should do it. restrict is not a keyword in C++, so #defineing it to nothing is unproblematic there.

Or, as Arne Mertz suggested, better still, have

extern "C" {
#define restrict
// include C headers here
#undef restrict
}

where you include the C headers in your C++ source.