AT&T UNIX™PC Unix System V Users Manual - tenox

CPP ( 1) CPP (1)
Two special names are understood by cpp . The name
_ _LINE __ is defined as the current line number (as a decimal
integer) as known by cpp, and __ 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
name.
All cpp directives start with lines begun by #. The directives are:
#define name token-string
Replace subsequent instances of name with token-string .
#define name( arg, ••• , arg ) token-string
Notice that there can be no space between name and the
(. Replace subsequent instances of name followed by a (,
a list of comma separated tokens, and a ) by token-string
where each occurrence of an arg in the token-string is
replaced by the corresponding token in the comma
separated list.
#undef name
Cause the definition of name (if any) to be forgotten from
now on.
#include "filename"
#include
Include at this point the contents of filename (which will
then be run through cpp ). When the notation
is used, filename is only searched for in the standard
places. See the -1 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" is not given, the current file
name is unchanged.
#end if
Ends a section of lines begun by a test directive (#if,
#ifdef, or #ifndef). Each test directive must have a
matching #endif.
#ifdef name
The lines following will 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 will 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.
#if constant-expression
Lines following will appear in the output if and only if the
constant-expression evaluates to non-zero. All binary
non-assignment C operators, the ?: operator, the unary - ,
I, and - operators are all legal in constant-expression .
The precedence of the operators is the same as defined by
- 2-
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