Xcode main.c File type is Puzzling

Question

Howdy,
In working through a C kinda book, I created several C projects. They run fine via Xcode and terminal using clang works fine on the main.c file. However while in terminal I ran the file command on the main.c file and got:
file main.c
main.c: ASCII C++ program text
I was expecting something along the lines of ". . . C program text".
So I tried:
$ clang++ main.c
clang: warning: treating 'c' input as 'c++' when in C++ mode, this behavior is deprecated
Interesting note, if I go into the project folder, duplicate and rename the copy to main.cpp, using clang++ works fine; no warning message
So my question --- is Xcode really creating a c++ file even when C was selected when making the project?  Just curious.

Answer 1

In the first case, the "file" command is an old UNIX tool that uses definitions in /usr/share/file/magic. It doesn't have any other meaning for the system. See the magic directory and/or "man file" for more information. In this case, it is confused by the "//" which it thinks indicate C++.
In the second case, you are simply trying to compile a C file with the C++ compiler. Clang works just like GCC in this respect. When you add the "++", it adds all of the necessary flags and include directories for C++. Even if you wrote straight up C code, there are some subtle differences between C and C++.