Red Hat ENTERPRISE LINUX 4 - USING CPP Using Instructions page 70

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-I
dir
Add the directory
Path. Directories named by
the directory
dir
default search order for system directories and the special treatment of system headers are not
defeated (Section 2.7 System Headers) .
-o
file
Write output to
. has a different interpretation of a second non-option argument, so you must use
cpp gcc
specify the output file.
-Wall
Turns on all optional warnings which are desirable for normal code. At present this is
,
-Wcomment -Wtrigraphs
change of sign in
default and have no options to control them.
-Wcomment
-Wcomments
Warn whenever a comment-start sequence
newline appears in a
-Wtrigraphs
Most trigraphs in comments cannot affect the meaning of the program. However, a trigraph that
would form an escaped newline (
begins or ends. Therefore, only trigraphs that would form escaped newlines produce warnings
inside a comment.
This option is implied by
are enabled. To get trigraph conversion without warnings, but get the other
-trigraphs -Wall -Wno-trigraphs
-Wtraditional
Warn about certain constructs that behave differently in traditional and ISO C. Also warn about
ISO C constructs that have no traditional C equivalent, and problematic constructs which should
be avoided. Chapter 10 Traditional Mode.
-Wimport
Warn the first time
-Wundef
Warn whenever an identifier which is not a macro is encountered in an
. Such identifiers are replaced with zero.
defined
-Wunused-macros
Warn about macros defined in the main file that are unused. A macro is used if it is expanded or
tested for existence at least once. The preprocessor will also warn if the macro has not been used
at the time it is redefined or undefined.
Built-in macros, macros defined on the command line, and macros defined in include files are
not warned about.
to the list of directories to be searched for header files. Section 2.3 Search
dir
are searched before the standard system include directories. If
-I
is a standard system include directory, the option is ignored to ensure that the
. This is the same as specifying
file
,
-Wmultichar
expressions. Note that many of the preprocessor's warnings are on by
#if
comment. (Both forms have the same effect.)
//
??/
. If
-Wall -Wall
is used.
#import
as the second non-option argument to
file
and a warning about integer promotion causing a
appears in a
/* /*
at the end of a line) can, by changing where the comment
is not given, this option is still enabled unless trigraphs
.
Chapter 12. Invocation
comment, or whenever a backslash-
-Wall
directive, outside of
#if
to
-o
warnings, use