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HP-UX 11i Version 3: February 2007

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cpp — the C language preprocessor


/usr/ccs/lbin/cpp [option]... [ifile [ofile]]


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.


The following options are recognized by cpp:


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.


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.



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.


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.


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.


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.


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.


Preprocess the input without producing the line-control information used by the next pass of the C compiler.


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.


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


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 __lint

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.


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:

#else #if constant-expression


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.


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.


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

Single- and multibyte character code sets are supported.


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.


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.



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


/usr/ccs/lbin/cpp t.c /var/tmp/ctmAAAa29220 -D__hp9000s700 -D__hp9000s800 ...

(Also see the -D option of the cc command.)



Standard directory for #include files




cpp: SVID2, SVID3, XPG2

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