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cpp
!!!cpp
NAME
SYNOPSIS
DESCRIPTION
OPTIONS
SEE ALSO
COPYING
----
!!NAME


cccp, cpp - The GNU C-Compatible Compiler Preprocessor.
!!SYNOPSIS


__cccp__


[[__-$__]
[[__-A__''predicate''[[__(__''value''__)__]]
[[__-C__]
[[__-D__''name''[[__=__''definition'']]
[[__-dD__] [[__-dM__] [[__-I__ ''directory'']
[[__-H__] [[__-I-__] [[__-imacros__ ''file'']
[[__-include__ ''file''] [[__-idirafter__ ''dir'']
[[__-iprefix__ ''prefix''] [[__-iwithprefix__
''dir''] [[__-lang-c__] [[__-lang-c++__]
[[__-lang-objc__] [[__-lang-objc++__] [[__-lint__]
[[__-M__ [[__-MG__]] [[__-MM__ [[__-MG__]]
[[__-MD__ ''file'' ] [[__-MMD__ ''file'' ]
[[__-nostdinc__] [[__-nostdinc++__] [[__-P__]
[[__-pedantic__] [[__-pedantic-errors__]
[[__-traditional__] [[__-trigraphs__]
[[__-U__''name''] [[__-undef__] [[__-Wtrigraphs__]
[[__-Wcomment__] [[__-Wall__] [[__-Wtraditional__]
[[''infile''|__-__]
[[''outfile''|__-__]
!!DESCRIPTION


The C preprocessor is a ''macro processor'' that is used
auto- matically by the C compiler to transform your program
be- fore actual compilation. It is called a macro processor
because it allows you to define ''macros'', which are
brief abbreviations for longer constructs.


The C preprocessor provides four separate facilities that
you can use as you see fit:


Inclusion of header files. These are files of dec- larations
that can be substituted into your pro- gram.


Macro expansion. You can define ''macros'', which are
abbreviations for arbitrary fragments of C code, and then
the C preprocessor will replace the macros with their
definitions throughout the program.


Conditional compilation. Using special preprocess- ing
directives, you can include or exclude parts of the program
according to various conditions.


Line control. If you use a program to combine or rearrange
source files into an intermediate file which is then
compiled, you can use line control to inform the compiler of
where each source line orig- inally came from.


C preprocessors vary in some details. For a full explana-
tion of the GNU C preprocessor, see the __info__ file
`__cpp.in- fo__', or the manual ''The C
Preprocessor''. Both of these are built from the same
documentation source file, `__cpp.texin- fo__'. The GNU C
preprocessor provides a superset of the features of ANSI
Standard C.


ANSI Standard C requires the rejection of many harmless
constructs commonly used by today's C programs. Such in-
compatibility would be inconvenient for users, so the GNU C
preprocessor is configured to accept these constructs by
default. Strictly speaking, to get ANSI Standard C, you must
use the options `__-trigraphs__', `__-undef__' and
`__-pedan- tic__', but in practice the consequences of
having strict ANSI Standard C make it undesirable to do
this.


Most often when you use the C preprocessor you will not have
to invoke it explicitly: the C compiler will do so
automatically. However, the preprocessor is sometimes useful
individually.


When you call the preprocessor individually, either name
(__cpp__ or __cccp__) will do--they are completely
synonymous.


The C preprocessor expects two file names as arguments,
''infile'' and ''outfile''. The preprocessor reads
''infile'' togeth- er with any other files it specifies
with `__#include__'. All the output generated by the
combined input files is writ- ten in
''outfile''.


Either ''infile'' or ''outfile'' may be `__-__',
which as ''infile'' means to read from standard input and
as ''outfile'' means to write to standard output. Also,
if ''outfile'' or both file names are omitted, the
standard output and standard input are used for the omitted
file names.
!!OPTIONS


Here is a table of command options accepted by the C pre-
processor. These options can also be given when compiling a
C program; they are passed along automatically to the
preprocessor when it is invoked by the
compiler.


__-P__


Inhibit generation of `__#__'-lines with line-number
information in the output from the preprocessor. This might
be useful when running the preprocessor on something that is
not C code and will be sent to a program which might be
confused by the `__#__'-lines.


__-C__


Do not discard comments: pass them through to the output
file. Comments appearing in arguments of a macro call will
be copied to the output before the expansion of the macro
call.


__-traditional__


Try to imitate the behavior of old-fashioned C, as opposed
to ANSI C.


__-trigraphs__


Process ANSI standard trigraph sequences. These are
three-character sequences, all starting with `__??__',
that are defined by ANSI C to stand for sin- gle characters.
For example, `__??/__' stands for `__\__', so
`__'??/n'__' is a character constant for a newline.
Strictly speaking, the GNU C preprocessor does not support
all programs in ANSI Standard C unless `__-trigraphs__'
is used, but if you ever notice the difference it will be
with relief.


You don't want to know any more about
trigraphs.


__-pedantic__


Issue warnings required by the ANSI C standard in certain
cases such as when text other than a com- ment follows
`__#else__' or `__#endif__'.


__-pedantic-errors__


Like `__-pedantic__', except that errors are produced
rather than warnings.


__-Wtrigraphs__


Warn if any trigraphs are encountered (assuming they are
enabled).


__-Wcomment__


__-Wcomments__


Warn whenever a comment-start sequence `__/*__' appears
in a comment. (Both forms have the same
effect).


__-Wall__


Requests both `__-Wtrigraphs__' and `__-Wcomment__'
(but not `__-Wtraditional__').


__-Wtraditional__


Warn about certain constructs that behave differ- ently in
traditional and ANSI C.


__-I__ ''directory''


Add the directory ''directory'' to the end of the list of
directories to be searched for header files. This can be
used to override a system header file, substituting your own
version, since these directo- ries are searched before the
system header file di- rectories. If you use more than one
`__-I__' option, the directories are scanned in
left-to-right order; the standard system directories come
after.


__-I-__


Any directories specified with `__-I__' options before
the `__-I-__' option are searched only for the case of
`__#include__ ''file''
''#in- clude ''''file''''


If additional directories are specified with `__-I__'
options after the `__-I-__', these directories are
searched for all `__#include__' directives.


In addition, the `__-I-__' option inhibits the use of the
current directory as the first search directory for
`__#include__ ''file''
''-I.__'. Specifying both `__-I-__' and
`__-I.__' allows you to control precisely which
directories are searched before the current one and which
are searched after.


__-nostdinc__


Do not search the standard system directories for header
files. Only the directories you have speci- fied with
`__-I__' options (and the current directory, if
appropriate) are searched.


__-nostdinc++__


Do not search for header files in the C++ specific standard
directories, but do still search the other standard
directories. (This option is used when building
libg++.)


__-D__ ''name''


Predefine ''name'' as a macro, with definition
`__1__'.


__-D__ ''name''__=__''definition''


Predefine ''name'' as a macro, with definition ''defini-
tion''. There are no restrictions on the contents of
''definition'', but if you are invoking the preproces-
sor from a shell or shell-like program you may need to use
the shell's quoting syntax to protect char- acters such as
spaces that have a meaning in the shell syntax. If you use
more than one `__-D__' for the same ''name'', the
rightmost definition takes ef- fect.


__-U__ ''name''


Do not predefine ''name''. If both `__-U__' and
`__-D__' are specified for one name, the `__-U__'
beats the `__-D__' and the name is not
predefined.


__-undef__


Do not predefine any nonstandard macros.


__-A__ ''name(''__value__'')''


Assert (in the same way as the __#assert__ directive) the
predicate ''name'' with tokenlist ''value''. Remember
to escape or quote the parentheses on shell command
lines.


You can use `__-A-__' to disable all predefined asser-
tions; it also undefines all predefined macros.


__-dM__


Instead of outputting the result of preprocessing, output a
list of `__#define__' directives for all the macros
defined during the execution of the prepro- cessor,
including predefined macros. This gives you a way of finding
out what is predefined in your version of the preprocessor;
assuming you have no file `__foo.h__', the
command


touch foo.h; cpp -dM foo.h


will show the values of any predefined macros.


__-dD__


Like `__-dM__' except in two respects: it does ''not''
in- clude the predefined macros, and it outputs ''both''
the `__#define__' directives and the result of prepro-
cessing. Both kinds of output go to the standard output
file.


__-M__ [[__-MG__]


Instead of outputting the result of preprocessing, output a
rule suitable for __make__ describing the de- pendencies
of the main source file. The preproces- sor outputs one
__make__ rule containing the object file name for that
source file, a colon, and the names of all the included
files. If there are many included files then the rule is
split into several lines using
`__\__'-newline.


`__-MG__' says to treat missing header files as gener-
ated files and assume they live in the same direc- tory as
the source file. It must be specified in addition to
`__-M__'.


This feature is used in automatic updating of make-
files.


__-MM__ [[__-MG__]


Like `__-M__' but mention only the files included with
`__#include__ __file''
''#include__ __file''
''


__-MD__ ''file''


Like `__-M__' but the dependency information is written
to `''file'''. This is in addition to compiling the file
as specified--`__-MD__' does not inhibit ordinary
compilation the way `__-M__' does.


When invoking gcc, do not specify the `''file''' argu-
ment. Gcc will create file names made by replacing
`__.c__' with `__.d__' at the end of the input file
names.


In Mach, you can use the utility __md__ to merge multi-
ple files into a single dependency file suitable for using
with the `__make__' command.


__-MMD__ ''file''


Like `__-MD__' except mention only user header files, not
system header files.


__-H__


Print the name of each header file used, in addi- tion to
other normal activities.


__-imacros__ ''file''


Process ''file'' as input, discarding the resulting
output, before processing the regular input file. Because
the output generated from ''file'' is discard- ed, the
only effect of `__-imacros__ ''file''' is to make the
macros defined in ''file'' available for use in the main
input. The preprocessor evaluates any `__-D__' and
`__-U__' options on the command line before pro- cessing
`__-imacros__ ''file''' .


__-include__ ''file''


Process ''file'' as input, and include all the result-
ing output, before processing the regular input
file.


__-idirafter__ ''dir''


Add the directory ''dir'' to the second include path. The
directories on the second include path are searched when a
header file is not found in any of the directories in the
main include path (the one that `__-I__' adds
to).


__-iprefix__ ''prefix''


Specify ''prefix'' as the prefix for subsequent
`__-iwithprefix__' options.


__-iwithprefix__ ''dir''


Add a directory to the second include path. The directory's
name is made by concatenating ''prefix'' and ''dir'',
where ''prefix'' was specified previously with
`__-iprefix__'.


__-lang-c__


__-lang-c++__


__-lang-objc__


__-lang-objc++__


Specify the source language. `__-lang-c++__' makes the
preprocessor handle C++ comment syntax, and in- cludes extra
default include directories for C++, and `__-lang-objc__'
enables the Objective C `__#import__' directive.
`__-lang-c__' explicitly turns off both of these
extensions, and `__-lang-objc++__' enables
both.


These options are generated by the compiler driver
__gcc__, but not passed from the `__gcc__' command
line.


__-lint__


Look for commands to the program checker __lint__ em-
bedded in comments, and emit them preceded by `__#pragma
lint__'. For example, the comment `__/* NOTREACHED
*/__' becomes `__#pragma lint__
NOTREACHED'.


This option is available only when you call __cpp__ di-
rectly; __gcc__ will not pass it from its command
line.


__-$__


Forbid the use of `__$__' in identifiers. This was
formerly required for strict conformance to the C Standard
before the standard was corrected. This option is available
only when you call __cpp__ direct- ly; __gcc__ will
not pass it from its command line.
!!SEE ALSO


`__Cpp__' entry in __info__; ''The C
Preprocessor'', Richard M. Stall- man.__
gcc__(__1__); `__Gcc__' entry in __info__;
''Using and Porting GNU CC (for version 2.0)'', Richard
M. Stallman.
!!COPYING


Copyright (c) 1991, 1992, 1993 Free Software Foundation,
Inc.


Permission is granted to make and distribute verbatim copies
of this manual provided the copyright notice and this
permission notice are preserved on all copies.


Permission is granted to copy and distribute modified ver-
sions of this manual under the conditions for verbatim
copying, provided that the entire resulting derived work is
distributed under the terms of a permission notice identical
to this one.


Permission is granted to copy and distribute translations of
this manual into another language, under the above con-
ditions for modified versions, except that this permission
notice may be included in translations approved by the Free
Software Foundation instead of in the original En-
glish.
----
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Last edited on Monday, June 3, 2002 6:50:02 pm by "perry"
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