I

Syntax

    -Idirectory 

Purpose
Specifies an additional search path if the file name in the #include directive is not specified using its absolute path name.

Notes
The value for directory must be a valid path name (for example, /u/golnaz, or /tmp, or ./subdir). The compiler appends a slash (/) to the directory and then concatenates it with the file name before doing the search. The path directory is the one that the compiler searches first for #include files whose names do not start with a slash (/). If directory is not specified, the default is to search the standard directories.

The normal search order is:

1. Search the directory where the current source file resides.
2. Search the directory or directories specified with the -I directory option.
3. Search the standard include directory, /usr/include.

If the -I directory option is specified both in the configuration file and on the command line, the paths specified in the configuration file are searched first.

When all specified directories have been searched, the directories on the standard list for #include files are searched. The directories on the standard list differ for the two versions of the #include directive. See Directory Search Sequence for Include Files Using Relative Path Names for more information about searching directories.

The -I directory option can be specified more than once on the command line. If you specify more than one -I option, directories are searched in the order that they appear on the command line.

If you specify a full (absolute) path name on the #include directive, this option has no effect.

Example
To compile myprogram.c and search /usr/tmp and then /oldstuff/history for included files, enter:

    xlC myprogram.c -I/usr/tmp -I/oldstuff/history

List of Compiler Options and Their Defaults
idirfirst Compiler Option