Gpc November 1997

gpc@gnu.de

32 participants
113 discussions

Accessing command line arguments example doesn't work
by Thomas_Tan＠fc.choate.edu 01 Nov '97

01 Nov '97

I get wierd errors when I try to compile the command line argument example. First it had a problem with the line (ParamStr := ";), so I changed the " to " " Then it said ( cmdline.pas(36) Error: undeclared identifier `Arg_num'" )about the line ( Success := _p_paramstr (arg_num, Str);) I don't know what's wrong. Here's the text I found in the Documentation of GPC: <********** begin text here *************> Accessing command line arguments: The following module accesses the command line with ParamStr and ParamCount functions. These follow the Un*x semantics, so that arg[0] == program name, arg[1] .. arg[ParamCount-1] are the arguments. MODULE command_line interface; EXPORT cmdline = (Max_length, Arg_type, ParamStr, ParamCount); CONST Max_length = 255; { Max length of each argument. If some arg is longer, the run time system traps it. } TYPE Arg_type = String(Max_length); FUNCTION ParamCount: Integer; FUNCTION ParamStr (arg_num: integer): Arg_type; END. { command_line interface } MODULE command_line implementation; { These are in the GPC runtime library } FUNCTION _p_paramcount : Integer; C; FUNCTION _p_paramstr (num: Integer; VAR str: String): Boolean; C; FUNCTION ParamCount; BEGIN ParamCount := _p_paramcount; END; { ParamCount } FUNCTION ParamStr; VAR Str : Arg_type; Success : Boolean; BEGIN Success := _p_paramstr (arg_num, Str); (* Should perhaps do something else on failure. * * Now it returns the empty string, which is also a valid * parameter. *) IF Success THEN ParamStr := Str else ParamStr := "; END; { ParamStr } END. { command_line implementation } { The program below, when compiled with the interface module and linked with the implementation module, accesses the command line arguments. } program zap (output); import cmdline; var counter : integer; begin writeln ('Program fetches command line arguments and outputs one per line'); writeln ('Max length of each argument is ',Max_Length:1,' characters'); for counter := 0 to ParamCount-1 do writeln ('Command line arg ',counter:1,' is "',paramstr(counter),'"'); end. <******************end text here****************> ------------------------------------------------------ This message sent using the FirstClass SMTP/NNTP Gateway. From: Choate Rosemary Hall 333 Christian St. Wallingford, CT. 06492

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Re: File Handling
by Peter Gerwinski 01 Nov '97

01 Nov '97

According to Thomas Tan: > I need to create a new text file, put some string in it, and save it to disk. Is > this possible in GPC? With gpc-971001 you can do it just like with Borland Pascal: Program Hello; Var MyFile: Text; S: String [ 42 ]; begin S:= 'Hello, world!'; Assign ( MyFile, 'hello.dat' ); rewrite ( MyFile ); writeln ( MyFile, S ); close ( MyFile ); end. Hope this helps, Peter Dipl.-Phys. Peter Gerwinski, Essen, Germany, free physicist and programmer peter.gerwinski(a)uni-essen.de - http://home.pages.de/~peter.gerwinski/ [971005] maintainer GNU Pascal [971001] - http://home.pages.de/~gnu-pascal/ [971005]

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Re: Editing GPC-source code
by Peter Gerwinski 01 Nov '97

01 Nov '97

According to Christian Bockermann: > > Sorry, if this does not really fit to Pascal-related programming, but I think it > fits to GPC !? Perfectly. :) > I have a question to all the people working on the improvement of GPC : > I want to insert a function of my own, written in C, into GPC. In which > file do I have to put it ? For example if I want to insert a function > of bpcompat direct into the compiler. Is there any way to do this ? While one can easily fill books with this topic, here is a short description what to do: * Locate your file in the `rts' subdirectory of the GPC source tree. (It may be written in C, Pascal, or any other GNU language, BTW.) * Edit `rts/Makefile.in', so your file will be compiled and included into `libgpc.a', GPC's run-time library. * In `util.c', add your routine to the `KItable'. * In `parse.y', assign a token to your routine, make it `%type <ttype>', add it to `new_identifier_1', so the identifier remains redefinable, and - implement it. For this last point, look at an existing routine which is called in a similar way as yours (`Assign', for instance, is a good example). * If your implementation in `parse.y' is through `rts_proc_parlist' or similar, the actual work will be done in `build_rts_call()'. So you will have to edit `rts.c' and to add your routine to the big `switch' statement in `build_rts_call()'. Depending on what you intend to implement, this can be quite easy or a nightmare. Again, look at an existing feature that is called in a similar way as yours. * Everywhere within GPC you will have to deal with so-called "tree nodes". I have written a short introduction to those things and more - see the chapter "GPC source" of the GPC online documentation. Good luck! If you succeed or have further questions, please let us know! Peter Dipl.-Phys. Peter Gerwinski, Essen, Germany, free physicist and programmer peter.gerwinski(a)uni-essen.de - http://home.pages.de/~peter.gerwinski/ [971005] maintainer GNU Pascal [971001] - http://home.pages.de/~gnu-pascal/ [971005]

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Gpc November 1997