CPP(1)

NAME
cpp - the C language preprocessor

SYNOPSIS
cpp [ -BCHMpPRT ] [ -undef ] [ -Dname ]
[ -Dname=val ] [ -Idirectory ] [ -Uname ]
[ -Ydirectory ] [ [input-file [output-file]] ]

DESCRIPTION
cpp is the C language preprocessor. This implementation does not implement the ANSI C standard but K&R.

cpp accepts up to two filenames as arguments. By default, cpp reads from standard input and writes to standard output. input-file and output-file are used to specify a different input or output for the preprocessor.

OPTIONS

-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 lines with cpp directives) to the output. The default is to suppress C-style comments and (if enabled via -B) C++-style comments.

-H  Print the path names of include files on standard error. Each name is printed on a separate line, names may appear more than once.

-M  Generates a list of dependencies and write them to the output. This list is in makefile format and indicates that the related .o file depends on the input file and the used include files.

-p  Only check for the first eight characters in macro names and issue a warning if extra tokens appear at the end of a line containing a directive.

-P  Do not include line control information in the preprocessor output.

-R  Allow recursive macros.

-T  Only check for the first eight characters in macro names. This option allows backwards compatibility with old systems that only check for the first eight characters.

-noinclude
    Remove the standard system include directory (usually /usr/include) from the search path.

-undef
    Remove all initially predefined macros.

-xsc
    Character constants are treated as signed char regardless of the default in the compiler.

-xuc
    Character constants are treated as unsigned char regardless of the default in the compiler.

-Dname
    Defines name as 1. This option has the same effect as if a

    #define name 1

    line was in the input file.

-Dname=val
    Defines name as val. This option has the same effect as if a

    #define name val

    line was in the input file.

-Idirectory
    Adds directory to the search path for #include directives.

-Uname
    Remove an initial definition of name.

-Ydirectory
    Uses directory instead of the standard system include directory.

USAGE

  Directives

All cpp directives start with a hash character (#) as the first character on a line. White space (SPACE or TAB characters) can appear after the initial # for indentation.

#define name value
    Replace subsequent instances of the text name with value.

#define name(argument [, argument] ... ) value
    Replaces each instance of name followed by a parenthesized list of arguments with value, where each occurrence of an argument in value is replaced by the corresponding token from the comma separated list of the actual parameters.

    A space between name and the `(' is not possible.

#undef name
    Remove any definition for the symbol name.

#ident text
    Forwards the line to the output. This is intended to be used by the compiler that usually puts the arguments into the comment section of the ELF binary.

#line line-number "filename"
Create control information for reading programs. The line-number must be an integer constant and is interpreted as the line number of the next line. filename is interpreted as the related filename. If "filename" is omitted, the current filename is not changed.

#include "filename"
#include <filename>
Reads the content of filename and handles it as if it was part of the current file. With the <filename> notation, filename is only searched in the list of standard include directories.

#if constant-expression
    If the constant-expression yields a non-zero expression, subsequent lines up to a matching #else, #elif or #endif appear in the output.

#ifdef name
    If name has been defined, subsequent lines up to a matching #else, #elif or #endif appear in the output.

#ifndef name
    If name has not been been defined, subsequent lines up to a matching #else, #elif or #endif appear in the output.

#elif constant-expression
    If the preceding #if, #ifdef, #ifndef or #elif directive did not include its block in the output and the constant-expression yields a non-zero expression, the following block of text is included in the output.

#else
    If the preceding conditional would include lines in the output, then lines between the #else and the matching #endif are ignored. If the preceding conditional would ignore lines, then lines between the #else and the matching #endif are included in the output. Conditional directives and corresponding #else directives can be nested.

#endif
    Marks the end of a section of lines begun by one of the conditional directives #if, #ifdef or #ifndef. Each such directive must have a matching #endif.

#pragma text
    Forwards the line to the output. This is intended to be used by the compiler that uses the related line as a way to forward directives.

#error text
    Prints text on stderr and exits with a non-zero exit status. If the #error directive is not inside a conditional active block, no error message is printed and the processing is not terminated.

EXAMPLES

ENVIRONMENT

SUNPRO_DEPENDENCIES
    The argument of this environment is used as a filename to output a make compatible dependency list. The output format is the same as with the -M option.

EXIT STATUS

The following exit codes are returned:

0   Successful completion.

1   An error occurred.

8   A command line syntax error occurred.

FILES

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

SEE ALSO

m4(1), mcs(1).

DIAGNOSTICS

NOTES
ANSI C preprocessors replace an escaped NEWLINE (a backslash that is immediately followed by a NEWLINE) with a SPACE. This implementation keeps backslash NEWLINE intact.

BUGS

AUTHOR
cpp was written by John F. Reiser in July/August 1978. This is a version enhanced by J. Schilling and maintained by J. Schilling since 2010.