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SunOS man pages : cpp (1)

User Commands                                              cpp(1)

NAME

cpp - the C language preprocessor

SYNOPSIS

/usr/lib/cpp [ -BCHMpPRT ] [ -undef ] [ -Dname ] [ - Dname = def ] [ -Idirectory ] [ -Uname ] [ -Ydirectory ] [ input-file [ output-file ] ]

DESCRIPTION

cpp is the C language preprocessor. It is invoked as the first pass of any C compilation started with the cc(1B) com- mand; however, cpp can also be used as a first-pass prepro- cessor for other Sun compilers. Although cpp can be used as a macro processor, this is not normally recommended, as its output is geared toward that which would be acceptable as input to a compiler's second pass. Thus, the preferred way to invoke cpp is through the cc(1B) command, or some other compilation command. For general-purpose macro-processing, see m4(1). cpp optionally accepts two filenames as arguments. input- file and output-file are, respectively, the input and output files for the preprocessor. They default to the standard input and the standard output.

OPTIONS

The following options are supported: -B Support the C++ comment indicator `//'. With this indicator everything on the line after the // is treated as a comment. -C Pass all comments (except those that appear on cpp directive lines) through the preprocessor. By default, cpp strips out C-style comments. -H Print the pathnames of included files, one per line on the standard error. -M Generate a list of makefile dependencies and write them to the standard output. This list indicates that the object file which would be generated from the input file depends on the input file as well as the include files referenced. -p Use only the first eight characters to distinguish preprocessor symbols, and issue a warning if extra tokens appear at the end of a line containing a direc- tive. -P Preprocess the input without producing the line SunOS 5.8 Last change: 1 Nov 1999 1 User Commands cpp(1) control information used by the next pass of the C compiler. -R Allow recursive macros. -T Use only the first eight characters for distinguishing different preprocessor names. This option is included for backward compatibility with systems which always use only the first eight characters. -undef Remove initial definitions for all predefined symbols. -Dname Define name as 1 (one). This is the same as if a -Dname=1 option appeared on the cpp command line, or as if a #define name 1 line appeared in the source file that cpp is process- ing. -Dname=def Define name as if by a #define directive. This is the same as if a #define name def line appeared in the source file that cpp is process- ing. The -D option has lower precedence than the -U option. That is, if the same name is used in both a -U option and a -D option, the name will be undefined regardless of the order of the options. -Idirectory Insert directory into the search path for #include files with names not beginning with `/'. directory is inserted ahead of the standard list of ``include'' directories. Thus, #include files with names enclosed in double-quotes (") are searched for first in the directory of the file with the #include line, then in directories named with -I options, and lastly, in directories from the standard list. For #include files with names enclosed in angle-brackets (<> ), the directory of the file with the #include line is not searched. See Details below for exact details of this search order. -Uname SunOS 5.8 Last change: 1 Nov 1999 2 User Commands cpp(1) Remove any initial definition of name, where name is a symbol that is predefined by a particular preproces- sor. Here is a partial list of symbols that may be predefined, depending upon the architecture of the system: Operating System: ibm, gcos, os, tss and unix Hardware: interdata, pdp11, u370, u3b, u3b2, u3b5, u3b15, u3b20d, vax, ns32000, iAPX286, i386, sparc, and sun UNIX system variant: RES, and RT The lint command: lint The symbols sun, sparc and unix are defined for all Sun systems. -Ydirectory Use directory directory in place of the standard list of directories when searching for #include files.

USAGE

Directives All cpp directives start with a hash symbol (#) as the first character on a line. White space (SPACE or TAB characters) can appear after the initial # for proper indentation. #define name token-string Replace subsequent instances of name with token- string. #define name(argument [, argument] ... ) token-string There can be no space between name and the `('. Replace subsequent instances of name, followed by a parenthesized list of arguments, with token-string, where each occurrence of an argument in the token- string is replaced by the corresponding token 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 re-starts its scan for names to expand at the beginning of the newly created token- string. #undef name SunOS 5.8 Last change: 1 Nov 1999 3 User Commands cpp(1) Remove any definition for the symbol name. No addi- tional tokens are permitted on the directive line after name. #include "filename" #include <filename> Read in the contents of filename at this location. This data is processed by cpp as if it were part of the current file. When the <filename> notation is used, filename is only searched for in the standard ``include'' directories. See the -I and -Y options above for more detail. No additional tokens are per- mitted on the directive line after the final `"' or `>'. #line integer-constant "filename" Generate line control information for the next pass of the C compiler. integer-constant is interpreted as the line number of the next line and filename is inter- preted as the file from where it comes. If "filename" is not given, the current filename is unchanged. No additional tokens are permitted on the directive line after the optional filename. #if constant-expression Subsequent lines up to the matching #else, #elif, or #endif directive, appear in the output only if constant-expression yields a nonzero value. All binary non-assignment C operators, including `&&', `||', and `,', are legal in constant-expression. The `?:' opera- tor, and the unary `-', `!', and `~' operators, are also legal in constant-expression. The precedence of these operators is the same as that for C. In addition, the unary operator defined, can be used in constant-expression in these two forms: `defined ( name )' or `defined name'. This allows the effect of #ifdef and #ifndef directives (described below) in the #if directive. Only these operators, integer constants, and names that are known by cpp should be used within constant-expression. In particu- lar, the size of operator is not available. #ifdef name Subsequent lines up to the matching #else, #elif, or #endif appear in the output only if name has been defined, either with a #define directive or a -D option, and in the absence of an intervening #undef directive. Additional tokens after name on the direc- tive line will be silently ignored. SunOS 5.8 Last change: 1 Nov 1999 4 User Commands cpp(1) #ifndef name Subsequent lines up to the matching #else, #elif, or #endif appear in the output only if name has not been defined, or if its definition has been removed with an #undef directive. No additional tokens are permitted on the directive line after name. #elif constant-expression Any number of #elif directives may appear between an #if, #ifdef, or #ifndef directive and a matching #else or #endif directive. The lines following the #elif directive appear in the output only if all of the fol- lowing conditions hold: o The constant-expression in the preceding #if directive evaluated to zero, the name in the preceding #ifdef is not defined, or the name in the preceding #ifndef directive was defined. o The constant-expression in all intervening #elif directives evaluated to zero. o The current constant-expression evaluates to non-zero. If the constant-expression evaluates to non-zero, sub- sequent #elif and #else directives are ignored up to the matching #endif. Any constant-expression allowed in an #if directive is allowed in an #elif directive. #else This inverts the sense of the conditional directive otherwise in effect. If the preceding conditional would indicate that lines are to be included, then lines between the #else and the matching #endif are ignored. If the preceding conditional indicates that lines would be ignored, subsequent lines are included in the output. Conditional directives and correspond- ing #else directives can be nested. #endif End a section of lines begun by one of the conditional directives #if, #ifdef, or #ifndef. Each such direc- tive must have a matching #endif. Macros Formal parameters for macros are recognized in #define directive bodies, even when they occur inside character con- stants and quoted strings. For instance, the output from: SunOS 5.8 Last change: 1 Nov 1999 5 User Commands cpp(1) #define abc(a)|`|a| abc(xyz) is: # 1 "" |`|xyz| The second line is a NEWLINE. The last seven characters are ``|`|xyz|'' (vertical-bar, backquote, vertical-bar, x, y, z, vertical-bar). Macro names are not recognized within char- acter constants or quoted strings during the regular scan. Thus: #define abc xyz printf("abc"); does not expand abc in the second line, since it is inside a quoted string that is not part of a #define macro defini- tion. Macros are not expanded while processing a #define or #undef. Thus: #define abc zingo #define xyz abc #undef abc xyz produces abc. The token appearing immediately after an #ifdef or #ifndef is not expanded. Macros are not expanded during the scan which determines the actual parameters to another macro call. Thus: #define reverse(first,second)second first #define greeting hello reverse(greeting, #define greeting goodbye ) produces `` #define hello goodbye hello''. Output Output consists of a copy of the input file, with modifica- tions, plus lines of the form: #lineno " filename" "level" SunOS 5.8 Last change: 1 Nov 1999 6 User Commands cpp(1) indicating the original source line number and filename of the following output line and whether this is the first such line after an include file has been entered (level=1), the first such line after an include file has been exited (level=2), or any other such line (level is empty). Details Directory Search Order #include files are searched for in the following order: 1. The directory of the file that contains the #include request (that is, #include is relative to the file being scanned when the request is made). 2. The directories specified by -I options, in left-to-right order. 3. The standard directory(s) (/usr/include on UNIX systems). Special Names Two special names are understood by cpp. The name __LINE__ is defined as the current line number (a decimal integer) as known by cpp, and __FILE__ is defined as the current filename (a C string) as known by cpp. They can be used any- where (including in macros) just as any other defined name. Newline Characters A NEWLINE character terminates a character constant or quoted string. An escaped NEWLINE (that is, a backslash immediately followed by a NEWLINE) may be used in the body of a #define statement to continue the definition onto the next line. The escaped NEWLINE is not included in the macro value. Comments Comments are removed (unless the -C option is used on the command line). Comments are also ignored, except that a com- ment terminates a token.

EXIT STATUS

The following exit values are returned: 0 Successful completion. non-zero An error occurred.

ATTRIBUTES

See attributes(5) for descriptions of the following attri- butes: SunOS 5.8 Last change: 1 Nov 1999 7 User Commands cpp(1) ____________________________________________________________ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | |_____________________________|_____________________________| | Availability | SUNWsprot | |_____________________________|_____________________________|

SEE ALSO

cc(1B), m4(1), attributes(5)

DIAGNOSTICS

The 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.

NOTES

When NEWLINE characters were found in argument lists for macros to be expanded, some previous versions of cpp put out the NEWLINE characters as they were found and expanded. The current version of cpp replaces them with <SPACE> charac- ters. Because the standard directory for included files may be different in different environments, this form of #include directive: #include <file.h> should be used, rather than one with an absolute path, like: #include "/usr/include/file.h" cpp warns about the use of the absolute pathname. While the compiler allows 8-bit strings and comments, 8-bits are not allowed anywhere else. SunOS 5.8 Last change: 1 Nov 1999 8