CPP(1) Amiga Programmer's Manual CPP(1) ›1mNAME cpp ›0m- C Pre Processor. Macro-preprocess C programs. ›1mSYNOPSIS ›0mcpp [-options] [infile [outfile]] ›1mDESCRIPTION ›0mCPP reads a C source file, expands macros and include files, and writes an input file for the C compiler. If no file arguments are given, CPP reads from stdin and writes to stdout. If one file argument is given, it will define the input file, while two file arguments define both input and output files. The file name "-" is a synonym for stdin or stdout as appropriate. The following options are supported. Options may be given in either case. -C   If set, source-file comments are written to the output file. This allows the output of CPP to be used as the input to a program, such as lint, that expects commands embedded in specially-formatted comments. -Dname=value Define the name as if the programmer wrote #define name value at the start of the first file. If "=value" is not given, a value of "1" will be used. On non-unix and non-amiga systems, all alphabetic text will be forced to upper-case. -E   Always return "success" to the operating system, even if errors were detected. Note that some fatal errors, such as a missing #include file, will terminate CPP, returning "failure" even if the -E option is given. -Idirectory Add this directory to the list of directories searched for #include "..." and #include <...> commands. Note that there is no space between the "-I" and the directory string. More than one -I command is permitted. On non-Unix systems "directory" is forced to upper-case. -N   CPP normally predefines some symbols defining the target computer and operating system. If -N is specified, no symbols will be predefined. If -N -N is specified, the "always present" symbols, __LINE__, __FILE__, __TIME__ and __DATE__ are not defined. -Stext CPP normally assumes that the size of the target computer's basic variable types is the same as the size of these types of the host computer. (This can be 1st PDC distribution -1- CPP(1) Amiga Programmer's Manual CPP(1) overridden when CPP is compiled, however.) The -S option allows dynamic respecification of these values. "text" is a string of numbers, separated by commas, that specifies correct sizes. The sizes must be specified in the exact order: char short int long float double If you specify the option as "-S*text", pointers to these types will be specified. -S* takes one additional argument for pointer to function (e.g. int (*)()) For example, to specify sizes appropriate for a PDP-11, you would write: c s i l f d func -S1,2,2,2,4,8, -S*2,2,2,2,2,2,2 Note that all values must be specified. ›3mNote also that this is not allowed by the 11-Jan-88 Draft, and therefore has made into an option when compiling Cpp. ›0m-Uname Undefine the name as if #undef name were given. On non-Unix systems, "name" will be forced to upper-case. -Xnumber Enable debugging code. If no value is given, a value of 1 will be used. (For maintenence of CPP only.) ›1mPre›0m-›1mDefined Variables ›0mWhen CPP begins processing, the following variables will have been defined (unless the -N option is specified): Target computer (as appropriate): pdp11, vax, M68000 m68000 m68k, amiga m68000 Target operating system (as appropriate): rsx, rt11, vms, unix, amigados Target compiler (as appropriate): decus, vax11c, pdc __PDC__ The implementor may add definitions to this list. The default definitions match the definition of the host computer, operating system, and C compiler. The following are always available unless undefined (or -N 1st PDC distribution -2- CPP(1) Amiga Programmer's Manual CPP(1) was specified twice): __FILE__    The input (or #include) file being compiled (as a quoted string). __LINE__    The line number being compiled. __DATE__    The date of compilation as a quoted string of the format "Mmm dd yyyy". __TIME__    The time of the start of compilation as a quoted string of the format "hh:mm:ss". Thus, printf("Bug at line %s,", __LINE__); printf(" source file %s", __FILE__); printf(" compiled on %s %s", __DATE__, __TIME__); ›1mSupported directives ›0m#assert #define #elif #else #endif #error #if #ifdef #ifndef #include #line #pragma #undef #debug #nodebug Unsupported # commands are copied verbatim into the output, so that maybe the compiler knows what to do with them. ›1mDraft Proposed Ansi Standard Considerations ›0mThe current version of the Draft Proposed Standard explicitly states that "readers are requested not to specify or claim conformance to this draft." Readers and users of Decus CPP should not assume that Decus CPP conforms to the standard, or that it will conform to the actual C Language Standard. When CPP is itself compiled, many features of the Draft Proposed Standard that are incompatible with existing preprocessors may be disabled. See the comments in CPP's source for details. The latest version of the Draft Proposed Standard (as reflected in Decus CPP) is dated November 12, 1984, and bits from K&R V2 are put in by Ois. Comments are removed from the input text. The comment is replaced by a single space character. The -C option preserves comments, writing them to the output file. The '$' character is considered to be a letter. This is a permitted extension. 1st PDC distribution -3- CPP(1) Amiga Programmer's Manual CPP(1) The following new features of C are processed by CPP: #if, #elif #elif expression (#else #if) '\xNNN' (Hexadecimal constant) '\a' (Ascii BELL) '\v' (Ascii Vertical Tab) #if defined NAME 1 if defined, 0 if not #if defined (NAME) 1 if defined, 0 if not #if sizeof (basic type) #error Generates error message unary + 123U, 123LU Unsigned ints and longs. 12.3L Long double numbers token##token Token concatenation in macros #macro-formal String generation in macros #include token Expands to filename The Draft Proposed Standard has extended C, adding a constant string concatenation operator, where "foo" "bar" is regarded as the single string "foobar". (This does not affect CPP's processing but does permit a limited form of macro argument substitution into strings as will be discussed.) The Standard Committee plans to add token concatenation to #define command lines. One suggested implementation is as follows: the sequence "Token1 ## Token2" is treated as if the programmer wrote "Token1Token2". This could be used as follows: #line 123 #define ATLINE foo ## __LINE__ ATLINE would be defined as foo123. Note that "Token1" and "Token2" both must be valid tokens, but the concatenation of their expanded forms may not be a _single_ valid token. In that case, K&R state that the behaviour is undefined. So if you wish to make portable use of this facility, do not do the following: #define cat(x, y) x ## y cat(foo, 1.23) which will produce foo1.23 and that is not a single token. If the tokens T1 and T2 are concatenated into T3, this implementation operates as follows: 1st PDC distribution -4- CPP(1) Amiga Programmer's Manual CPP(1) 1. Expand T1 if it is a macro. 2. Expand T2 if it is a macro. 3. Join the tokens, forming T3. 4. Rescan T3, looking for tokens, that may be expanded again. A macro formal parameter will be substituted into a string or character constant if it is the only component of that constant: #define VECSIZE 123 #define vprint(name, size) \ printf("name" "[" "size" "] = {\n") ... vprint(vector, VECSIZE); expands (effectively) to vprint("vector[123] = {\n"); Note that this will be useful if your C compiler supports the new string concatenation operation noted above. As implemented here, if you write #define string(arg) "arg" ... string("foo") ... This implementation generates "foo", rather than the strictly correct ""foo"" (which will probably generate an error message). This is, strictly speaking, an error in CPP and may be removed from future releases. ›3mNote that the above feature of replacing macro formals inside quotes is non-standard. The Committee thought the following to be better: ›0mIf a macro formal argument is immediately preceeded by a #, the argument supplied when expanding the macro will be surrounded by double quotes, and each double quote or backslash will be preceeded by a backslash. An example of this would be: #define string(arg) #arg ... string(foo) ... which produces "foo". Note that this feature is useless if you want your string to contain an odd number of quotes: string(Hello"); will produce an error message, complaining about unterminated strings. ›1mError messages ›0mMany. CPP prints warning or error messages if you try to use multiple-byte character constants (non-transportable) if you #undef a symbol that was not defined, or if your program has potentially nested comments. 1st PDC distribution -5- CPP(1) Amiga Programmer's Manual CPP(1) ›1mAuthor ›0mMartin Minow, minor changes by RMS, FNF, OIS. ›1mBugs ›0mThe #if expression processor uses signed integers only. I.e, #if 0xFFFFu < 0 may be TRUE. 1st PDC distribution -6-