Does extern “C” have any effect in C?

Question

I just got some C code that uses extern \"C\" to declare external functions like this:

extern \"C\" void func();

Is this valid C? I\'m getting

Answer 1

Not valid in C. If present after preprocessing this will result in a diagnostic as per the standard.

For C++, this turns of name-mangling. See this for more details as to why it may be required. Can you post some more details?