Performs file inclusion and macro substitution on C language source files.
/usr/ccs/lib/cpp [ -C ] [ -P ] [ -qDBCS ] [ -IDirectory ] [ -UName ] [ -DName [ =Defin ition ] ] [ -qlanglvl=Language ] [ InFile ] [ OutFile ]
The cpp command performs file inclusion and macro substitution on C language source files. It reads InFile and writes to OutFile (standard input and standard output by default).
The cpp command is designed to conform to the preprocessing directives and instructions for the C language as defined by the document "Draft American National Standard for Information Systems - Programming Language C" (X3J11/88-159).
The cpp program
recognizes the following special names:
|__LINE__||The current line number.|
|__DATE__||The date of translation of the source file.|
|__TIME__||The time of translation of the source file.|
|__STDC__||Indicates a conforming implementation.|
|__FILE__||The current file name.|
|__STR__||Indicates the compiler will generate inline code for certain string functions (as defined in /usr/include/string.h).|
|__MATH__||Indicates the compiler will generate inline code for certain math functions (as defined in /usr/include/math.h).|
|__ANSI__||Indicates langlvl is set equal to ANSI.|
|__SAA__||Indicates langlvl is set equal to SAA.|
|__SAA_L2__||Indicates langlvl is set equal to SAAL2.|
|__EXTENDED__||Indicates langlvl is set equal to extended.|
|__TIMESTAMP__||Indicates the date and time when the source file was last modified.|
All cpp directive lines
must begin with a # (pound sign). These directives
|#define Name TokenString||Replaces subsequent instances of Name with TokenString.|
|#define Name(Argument,...,Argument) TokenString||Replaces subsequent instances of the sequence Name (Argument, . . . ,Argument) with TokenString, where each occurrence of an Argument in TokenString is replaced by the corresponding token in the comma-separated list. Note that there must not be any space between Name and the left parenthesis.|
|#undef Name||Ignores the definition of Name from this point on.|
|#include "File" or #include <File>||Includes at this point the contents of File, which
cpp then processes.
If you enclose File in " " (double quotation marks) the cpp command searches first in the directory of InFile, second in directories named with the -I flag, and last in directories on a standard list.
|#line Number ["File"]||Causes the implementation to behave as if the following sequence of source lines begins with a source line that has a line number as specified by Number. If File is supplied, the presumed name of the file is changed to be File.|
|#error TokenString||Produces a diagnostic message that includes TokenString.|
|#pragma TokenString||An implementation-defined instruction to the compiler.|
|#endif||Ends a section of lines begun by a test directive (#if, #ifdef, or #ifndef). Each test directive must have a matching #endif.|
|#ifdef Name||Places the subsequent lines in the output only if:|
|#ifndef Name||Places the subsequent lines in the output only if:|
|#if Expression||Places subsequent lines in the output only if Expression
evaluates to nonzero. All the binary nonassignment C operators, the
?: operator, and the unary -, !, and - operators are legal in
Expression. The precedence of the operators is the same as
that defined in the C Language. There is also a unary operator
defined, which can be used in Expression in these two
|#elif Expression||Places subsequent lines in the output only if the expression in the preceding #if or #elif directive evaluates to false or is undefined, and this Expression evaluates to true.|
|#else||Places subsequent lines in the output only if the expression in the
preceding #if or #elif directive evaluates to false or
is undefined (and hence the lines following the #if and preceding
the #else have been ignored).
Each test directive's condition is checked in order. If it evaluates to false (0), the group that it controls is skipped. Directives are processed only through the name that determines the directive in order to keep track of the level of nested conditionals; the rest of the directives' preprocessing tokens are ignored, as are the other preprocessing tokens in the group. Only the first group whose control condition evaluates to true (nonzero) is processed. If none of the conditions evaluates to true, and there is a #else directive, the group controlled by the #else is processed; lacking a #else directive, all the groups until the #endif are skipped.
|-C||Copies C language comments from the source file to the output file. If you omit this flag, the cpp command removes all C language comments except those found on a cpp directive line.|
|-DName[=Definition]||Defines Name as in a #define directive. The default Definition is 1.|
|-IDirectory||Looks first in Directory, then looks in the directories on the standard list for #include files with names that do not begin with a / (slash). See the previous discussion of #include.|
|-P||Preprocesses input without producing line control information for the next pass of the C compiler.|
|-qDBCS||Specifies double-byte character set mode.|
|-UName||Removes any initial definition of Name, where Name is a symbol predefined by the preprocessor (except for the four preprocessor mode indicators: __ANSI__, __EXTENDED__, __SAA__, and __SAA_L2__). This flag is not recognized in ANSI mode.|
|-qlanglvl=Language||Selects a language level for processing. Language can
be ANSI, SAA, SAAL2, or extended. The default is extended.
Note: When Language is extended, _NO_PROTO is not automatically defined. Such definition can be done using the -D option in the /etc/xlc.cfg file.
This preprocesses pgm.c and displays the resulting text at the work station. You may want to see the preprocessor output when looking for errors in your macro definitions.
/usr/ccs/lib/cpp -P -C pgm.c pgm.i
This preprocesses pgm.c and stores the result in pgm.i. It omits line numbering information intended for the C compiler (-P), and includes program comments (-C).
/usr/ccs/lib/cpp -DBUFFERSIZE=512 -DDEBUG pgm.c pgm.i
This defines BUFFERSIZE with the value 512 and DEBUG with the value 1 before preprocessing.
/usr/ccs/lib/cpp -I/home/jim/include pgm.c
This looks in the current directory for quoted #include files, then in /home/jim/include, and then in the standard directories. It looks in /home/jim/include for angle-bracketed #include files (< >) and then in the standard directories.
/usr/ccs/lib/cpp -qlanglvl=ansi pgm.c
|/usr/include||Standard directory for #include files.|
The m4 command.