These options affect how the cpp preprocessor searches
for files specified via the #include directive.
Therefore, when compiling Fortran programs, they are meaningful
when the preprocessor is used.
Some of these options also affect how g77 searches
for files specified via the INCLUDE directive,
although files included by that directive are not,
themselves, preprocessed.
These options are:
-I-
-IdirINCLUDE directive
(as well as of the #include directive of the cpp
preprocessor).
Note that -Idir must be specified without any
spaces between -I and the directory name--that is,
-Ifoo/bar is valid, but -I foo/bar
is rejected by the g77 compiler (though the preprocessor supports
the latter form).
Also note that the general behavior of -I and
INCLUDE is pretty much the same as of -I with
#include in the cpp preprocessor, with regard to
looking for header.gcc files and other such things.
See Options for Directory Search, for information on the
-I option.