Compilation C, C++, Objective-C et Objective-C++ on Mac - objective-c

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.