cpp(1) cpp(1)
NAME [Toc] [Back]
cpp - the C language preprocessor
SYNOPSIS [Toc] [Back]
/usr/ccs/lbin/cpp [option ...] [ifile [ofile]]
DESCRIPTION [Toc] [Back]
cpp is the C language preprocessor which is invoked as the first pass
of any C compilation using the cc command (see cc(1)). Its purpose is
to process #include and conditional compilation instructions and
macros. Thus the output of cpp is designed to be in a form acceptable
as input to the next pass of the C compiler. As the C language
evolves, cpp and the rest of the C compilation package will be
modified to follow these changes. Therefore, the use of cpp in other
than this framework is not suggested. The preferred way to invoke cpp
is through the cc command, since the functionality of cpp may someday
be moved elsewhere. See m4(1) for a general macro processor.
cpp optionally accepts two file names as arguments. ifile and ofile
are respectively the input and output for the preprocessor. They
default to standard input and standard output if not specified.
Options [Toc] [Back]
The following options are recognized by cpp:
-A Remove all predefined symbols that begin with a letter
and _HPUX_SOURCE. The user is expected to define
_POSIX_SOURCE or _XOPEN_SOURCE when using this option.
-C By default, cpp strips C-style comments. If the -C
option is specified, all comments (except those found
on cpp directive lines) are passed along.
-Dname
-Dname=def Define name as if by a #define directive. If no =def
is given, name is defined as 1. The -D option has
lower precedence than the -U option. Thus, if the same
name is used in both a -U option and a -D option, the
name is undefined regardless of the order of the
options.
-Hnnn Change the internal macro definition table to be nnn
bytes in size. The default buffer size is at least
8188 bytes. This option serves to eliminate ``Macro
param too large'', ``Macro invocation too large'',
``Macro param too large after substitution'', ``Quoted
macro param too large'', ``Macro buffer too small'',
``Input line too long'', and ``Catenated input line too
long'' errors.
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-h[inclfile] Generates included files and sents the results to the
file inclfile. If the argument inclfile is omitted,
the result is sent to the standard error.
-Idir Change the algorithm for searching for #include files
whose names do not begin with / to look in dir before
looking in the directories on the standard list. Thus,
#include files whose names are enclosed in double
quotes ("") are searched for first in the directory of
the file containing the #include line, then in
directories named in -I options in left-to-right order,
and last in directories on a standard list. For
#include files whose names are enclosed in angle
brackets (<>), the directory of the file containing the
#include line is not searched. However, directory dir
is still searched.
-M[makefile] Generates makefile dependencies and sends the results
to the file makefile. If the argument makefile is
omitted, the result is sent to the standard error.
-P Preprocess the input without producing the line-control
information used by the next pass of the C compiler.
-T HP-UX no longer restricts preprocessor symbols to eight
characters. The -T option forces cpp to use only the
first eight characters for distinguishing different
preprocessor names. This behavior is the same as
preprocessors on some other systems with respect to the
length of names, and is included for backward
compatibility.
-Uname Remove any initial definition of name, where name is a
reserved symbol that is predefined by the particular
preprocessor. The current list of these symbols
includes:
Operating system: unix __unix
Hardware: hp9000s200 hp9000s300 __hp9000s300
hp9000s500 hp9000s800 __hp9000s800
hp9000ipc hppa __hppa
_PA_RISC1_0 _PA_RISC1_1 _SIO _WSIO
UNIX systems variant: hpux __hpux
_HPUX_SOURCE PWB
_PWB
lint(1): lint __lint
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In addition, all symbols that begin with an underscore
and either an upper-case letter or another underscore
are reserved. Other symbols may be defined by the
CCOPTS variable or other command-line options to the C
compiler at compile time (see cc(1)). All HP-UX
systems have the symbols PWB, hpux, unix, _PWB, __hpux,
and __unix defined. Each system defines at least one
hardware variant, as appropriate. The lint symbols are
defined when lint(1) is running. See DEPENDENCIES.
Two special names are understood by cpp. __LINE__ is defined as the
current line number (as a decimal integer) as counted by cpp.
__FILE__ is defined as the current file name (as a C string) as known
by cpp. They can be used anywhere (including in macros) just as any
other defined names.
Directives [Toc] [Back]
All cpp directives start with lines begun by #. Any number of blanks
and tabs are allowed between the # and the directive. The directives
are:
#define name token-string
Replace subsequent instances of name with token-string.
token-string can be null.
#define name(arg, ... , arg) token-string
Replace subsequent instances of name followed by a (, a
list of comma-separated set of arguments, and a ) by
token-string, where each occurrence of an arg in the
token-string is replaced by the corresponding set of
tokens in the comma-separated list. When a macro with
arguments is expanded, the arguments are placed into
the expanded token-string unchanged. After the entire
token-string has been expanded, cpp restarts its scan
for names to expand at the beginning of the newly
created token-string.
Notice that there can be no space between name and the
(.
#endif [text] Ends a section of lines begun by a test directive (#if,
#ifdef, or #ifndef). Each test directive must have a
matching #endif. Any text occurring on the same line
as the #endif is ignored and thus may be used to mark
matching #if-#endif pairs. This makes it easier, when
reading the source, to match #if, #ifdef, and #ifndef
directives with their associated #endif directive.
#elif constant-expression
Equivalent to:
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#else
#if constant-expression
#else Reverses the notion of the test directive that matches
this directive. Thus, if lines previous to this
directive are ignored, the following lines appear in
the output, and vice versa.
#if constant-expression
The lines following appear in the output if and only if
the constant-expression evaluates to nonzero. All
binary nonassignment C operators, the ?: operator, the
unary -, !, and ~ operators are all legal in constant-
expression. The precedence of the operators is the
same as defined by the C language.
There is also a unary operator, defined, which can be
used in constant-expression in these two forms:
defined(name) or defined name. This allows the use of
#ifdef and #ifndef in an #if directive.
Only these operators, integer constants, and names that
are known by cpp should be used in constant-expression.
In particular, the sizeof operator is not available.
#ifdef name The lines following appear in the output if and only if
name has been the subject of a previous #define without
being the subject of an intervening #undef.
#ifndef name The lines following do not appear in the output if and
only if name has been the subject of a previous #define
without being the subject of an intervening #undef.
#include "filename"
#include <filename>
Include at this point the contents of filename (which
are then run through cpp). See the -I option above for
more detail.
#line integer-constant "filename"
Causes cpp to generate line-control information for the
next pass of the C compiler. integer-constant is the
line number of the next line and filename is the file
where it comes from. If filename and the quotation
marks are omitted, the current file name is unchanged.
#undef name Cause the definition of name (if any) to be forgotten
from now on.
The test directives and the possible #else directives can be nested.
cpp supports names up to 255 characters in length.
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Notes [Toc] [Back]
The macro substitution scheme has been changed. Previous versions of
cpp saved macros in a macro definition table whose table size is
128000 bytes by default. The current version of cpp replaces this
macro definition table with several small buffers. The default size
of the small buffers is 8188 bytes.
EXTERNAL INFLUENCES [Toc] [Back]
Environment Variables
LC_CTYPE determines the interpretation of comments and string literals
as single- or multibyte characters.
LANG determines the language in which messages are displayed.
If LC_CTYPE is not specified in the environment or is set to the empty
string, the value of LANG is used as a default for each unspecified or
empty variable. If LANG is not specified or is set to the empty
string, it defaults to "C" (see lang(5)). If any internationalization
variable contains an invalid setting, cpp behaves as if all
internationalization variables are set to "C". See environ(5).
International Code Set Support [Toc] [Back]
Single- and multibyte character code sets are supported.
DIAGNOSTICS [Toc] [Back]
Error messages produced by cpp are intended to be self-explanatory.
The line number and filename where the error occurred are printed
along with the diagnostic.
WARNINGS [Toc] [Back]
When newline characters were found in argument lists for macros to be
expanded, previous versions of cpp put out the newlines as they were
found and expanded. The current version of cpp replaces these
newlines with blanks to alleviate problems that the previous versions
had when this occurred.
DEPENDENCIES [Toc] [Back]
Workstation
The symbols hp9000s700 and __hp9000s700 are not reserved symbols
recognized by the -U option. They are supplied to cpp either
automatically by the compiler, or by the use of a compiler option.
For example, on a Series 700 system, the command:
cc -v t.c
produces:
/usr/ccs/lbin/cpp t.c /var/tmp/ctmAAAa29220 -D__hp9000s700
-D__hp9000s800 ...
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(Also see the -D option of the cc command.)
FILES [Toc] [Back]
/usr/include Standard directory for #include files
SEE ALSO [Toc] [Back]
m4(1).
STANDARDS CONFORMANCE [Toc] [Back]
cpp: SVID2, SVID3, XPG2
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