Question

I use CPLUS_INCLUDE_PATH environment variable to compile .cpp files and it works fine to find .h files.

But it’s not ok to compile ObjC or ObjC++.

Do you know the good one variable.

Thanks.

Answer 1

From the manual page:

   CPATH
   C_INCLUDE_PATH
   CPLUS_INCLUDE_PATH
   OBJC_INCLUDE_PATH
       Each variable’s value is a list of directories separated by a
       special character, much like PATH, in which to look for header
       files.  The special character, "PATH_SEPARATOR", is target‐
       dependent and determined at GCC build time.  For Microsoft Windows‐
       based targets it is a semicolon, and for almost all other targets
       it is a colon.

       CPATH specifies a list of directories to be searched as if
       specified with −I, but after any paths given with −I options on the
       command line.  This environment variable is used regardless of
       which language is being preprocessed.

       The remaining environment variables apply only when preprocessing
       the particular language indicated.  Each specifies a list of
       directories to be searched as if specified with −isystem, but after
       any paths given with −isystem options on the command line.

       In all these variables, an empty element instructs the compiler to
       search its current working directory.  Empty elements can appear at
       the beginning or end of a path.  For instance, if the value of
       CPATH is ":/special/include", that has the same effect as
       −I. −I/special/include.