Question

I have an externally provided .cpp file. It is a mixture of C compatible code and a bit of C++ as well. The C++ code is just a wrapper around the C to take advantage of C++ features.

It uses #ifdef __cplusplus macros to protect the C++ code, which is great. Unfortunately, if I try to compile using GCC, it treats it as C++ because of the file ending. I’m aware of the differences between gcc and g++ – I don’t want to compile as C++.

Is there any way I can force GCC to treat this file as a C file? I’ve tried using e.g. --std=c99, but this correctly produces the error that C99 isn’t valid for C++.

Renaming the file to .c works, but I’d like to avoid this if possible because it’s externally provided and it’d be nice for it to remain as a pristine copy.

Answer 1

The -x option for gcc lets you specify the language of all input files following it:

$ gcc -x c your-file-name.cpp

If you only want to special-case that one file, you can use -x none to shut off the special treatment:

$ gcc -x c your-filename.cpp -x none other-file-name.cpp

(your-filename.cpp will be compiled as C, while other-file-name.cpp will use the extension and compile as C++)