Gpc March 1998

gpc@gnu.de

21 participants
37 discussions

Pi
by Miklos Cserzo 20 Mar '98

20 Mar '98

Hi Folks, the constat "Pi" apparently is not declared by default in my system. (IRIX 6.2, GPC 2.0) Am I missing something? miklos

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Any good Documentation TXT,HTM,...
by OHMH＠nets.com.jo 20 Mar '98

20 Mar '98

Is there any good Documentation for the GNU-Pascal Compiler, something like a programmers reference, or like the Borland's Help ... Thanks a lot Omer

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Re: reset
by Frank Heckenbach 19 Mar '98

19 Mar '98

Miklos Cserzo wrote: > the following construction fails: > > assign(ip,'input_file'); reset(ip); > > repeat > readln(ip,...... > until eof(ip); > > reset(ip); { <<<< This is the point where the shit hits the fan... } > > > I think it is legal. (It is surely OK under TP.) > > I am running IRIX 6.2, GPC 2.0. It works for me. I just tried the following program under Linux, and it correctly prints the first line of input_file. program x; var ip:text; s:string(100); begin assign(ip,'input_file'); reset(ip); repeat readln(ip); until eof(ip); reset(ip); readln(ip,s); writeln(s); close(ip); end. Doesn't this program work under IRIX? Otherwise please send a complete program that doesn't work. Oh well, maybe it didn't work in GPC 2.0. You might want to try a newer beta version. Jesper Lund wrote: > In GPC you need to close the file before calling reset/rewrite again. Add the > statement 'close(ip)' before the second reset, and everything should work. > > This issue has been raised before on the mailing list, but I am not sure > whether it is bug or a feature..... AFAIR, the problem that was discussed was that GPC closes the file and re-opens it, instead of just seeking to the beginning. This is a bit inefficient and has (I think) some other disadvantages, but does not mean that it doesn't work at all. -- Frank Heckenbach, Erlangen, Germany fjf(a)gmx.de http://home.pages.de/~fjf/links.htm

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Re: system()
by Frank Heckenbach 18 Mar '98

18 Mar '98

Jim Roland wrote: > It works beautifully, but you must include the definition in your > procedures/functions section: > > Procedure system ( parameters ); C; > or > Function system ( parameters ); C; > > I don't remember the parameters for the system() function, but > "man system" should tell you. Yes, the man page says "char *" which is "CString" in GPC. > The C; at the end is important and the > "system" as opposed to "System" or "SYSTEM" is important too. Not really. The "C;" directive will transform all identifiers to lower case internally. I used "System" in the example I just posted, and this works, too. If one needs upper or mixed case C identifiers, one can use asmname like "procedure Foo; asmname 'bAr';" or whatever. -- Frank Heckenbach, Erlangen, Germany fjf(a)gmx.de http://home.pages.de/~fjf/links.htm

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Re: Append Text Files, Exec()
by Frank Heckenbach 18 Mar '98

18 Mar '98

> > Otherwise you can simply call the system() function. The declaration is: > > > > function System (CmdLine: CString): Integer; C; > > > > (CString is the same as PChar in BP, and newer versions of GPC understand > > both CString and PChar.) > > Frank, > > Thanks for the info. If it's not too much to ask, could you send me a > sample program that uses the system() function. I have not yet explored > the depths of CStrings, and need to get some programs to function properly > in a short period of time. Try the program below. (* Note: The function Str2CStrRO converts a Pascal string into a CString. It's about the same as BP's StrPCopy. I called it Str2CStr rather than StrPCopy because this seems clearer to me, and I appended "RO" (read-only) to make it clear that neither the Pascal string nor the CString should be modified while the CString is used. Future versions of GPC should have something like this built-in, but for now, one has to do it manually. *) The rest of the program should be straightforward. Unlike BP's Exec, you don't have to specify the program and paramters in two separate strings, but rather combined into one string (with a space between them). Also, you don't have to give the full path to the program when the program is located in the system path. So, you could test it with a command like "command /s dir" for Dos or "ls -la" for Unix. program Exec_Demo; function System (cmd: CString): Integer; C; function Str2CStrRO (var s: String): CString; begin s[Length(s)+1] := #0; Str2CStrRo := @s[1] end; var s: String (1000); i: Integer; begin Write ('Enter a system command: '); Readln (s); i := System (Str2CStrRO (s)); Writeln ('The returned status of the system was ', i, '.') end. > The extend() procedure seems to tack on a newline & carriage return onto > the end of the text file before any writing can be done to the file. (* Only if there isn't one already. *) > Is this a bug/feature? It's a feature! :-) The Extended Pascal standard demands this, and actually it took a bit of extra code within the RTS to implement this behaviour. > Is there a fix/way to get around this? AFAIK, there's no way to prevent this (except using a file of char and seeking to the end, but then the formatting of Write[ln] isn't available -- only via WriteStr)-: Perhaps it would be useful to have a GPC switch to turn this behaviour off, perhaps coupled to the --borland-pascal switch? Any comments, also from the mailing list (to which I'm sending a copy)? -- Frank Heckenbach, Erlangen, Germany fjf(a)gmx.de http://home.pages.de/~fjf/links.htm

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system()
by Geoffrey Arnold 18 Mar '98

18 Mar '98

When I try to make a call to the system() procedure, I get this compiler error: testex.p: In function `program_Testex': testex.p:4: undeclared identifier `System' (first use this function) testex.p:4: (Each undeclared identifier is reported only once testex.p:4: for each function it appears in.) Is there something else I must include in my program? I am using gpc-2.0 compiled for the linux 2.0 platform. ----Geoffrey Arnold--- garnold(a)cyberdrive.net

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Re: Append Text Files, Exec()
by Frank Heckenbach 17 Mar '98

17 Mar '98

Geoffrey Arnold wrote: > Is there and append() or similar procedure that allows me to write > directly to the end of text files? > If you have any information, please contact me directly by email. It's called Extend. The only difference to BP's Apped (AFAIK) is that Extend creates the file if it doesn't exist. > Is there an exec() or similar procedure supported by GPC that allows the > execution of external programs? Not built-in, but if you're using GPC on a Dos platform, you might want to get the BPCompat package from ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/contrib/ whose Dos unit contains an Exec procedure. Otherwise you can simply call the system() function. The declaration is: function System (CmdLine: CString): Integer; C; (CString is the same as PChar in BP, and newer versions of GPC understand both CString and PChar.) -- Frank Heckenbach, Erlangen, Germany fjf(a)gmx.de http://home.pages.de/~fjf/links.htm

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Exec()
by Geoffrey Arnold 17 Mar '98

17 Mar '98

Is there an exec() or similar procedure supported by GPC that allows the execution of external programs? If you have any information, please contact me direct by email. Thanks. Geoffrey Arnold garnold(a)cyberdrive.net

1 0

Append()
by Geoffrey Arnold 17 Mar '98

17 Mar '98

Is there an append() or similar procedure that allows me to write directly to the end of text files? If you have any information, please contact me direct by email. Thanks. Geoffrey Arnold garnold(a)cyberdrive.net

1 0

Exec()
by Geoffrey Arnold 17 Mar '98

17 Mar '98

Is there an exec() or similar procedure supported by GPC that allows the execution of external programs? If you have any information, please contact me directly by email. Thanks. Geoffrey Arnold garnold(a)cyberdrive.net

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Gpc March 1998