Question

Lets say I have a C++ program and I want to call functions from a C object file in it. The constraint is that I’m not allowed to make any changes to the C source files.

In this case I would include the C header as extern “C” in my C++ file, call the function, compile the C object using gcc -c, and pass the result to g++ along with the actual C++ sources.

I guess what I would also do is to put the C-header #include inside a named namespace block in the C++ file, as to keep the local namespace clean (who knows what other fancy stuff there is in the .h file).

What now if I need to call functions from two C object files. Lets say that they have different signatures. But there are also some duplicate functions in the object files. Wouldn’t my linker blow up at this point if I tried to pass both objects to g++ at the same time? Same for globals.

Again: I’m not allowed to change ANY of the C sources. Else I would just rename the .c files to .cxx, wrap their contents and the contents of the corresponding headers inside namespace bla { } and feed everything to g++.

(Yes, C is not a subset of C++, as has already been mentioned in one of the comments)

Answer 1

Your last paragraph has a good solution – why not make a C++ file something like this:

namespace c_namespace_1 {
    #include "CFile1.c"
}

namespace c_namespace_2 {
    #include "CFile2.c"
}

And so on…. then you could compile this file as C++ and not have to modify the original sources.