Gpc November 2002

gpc@gnu.de

33 participants
48 discussions

Questions about coding...
by Andrew McCall 06 Nov '02

06 Nov '02

Hi All, After years of missing THINKS Pascal on the Mac, I thought I would give gpc a quick try! It seems pretty cool too! The first question I wanted to ask is about this list - can I ask coding questions here, or is it purley for actual gpc development? -- Thanks, Andrew McCall Internet/Linux System Administrator I.C.T. Division Oldham MBC Civic Centre West Street Oldham OL1 1UU Tel : 0161 911 3990 Fax : 0161 911 3998 Email : it.andrew.mccall(a)oldham.gov.uk ********************************************************************** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.oldham.gov.uk **********************************************************************

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Re: Questions about coding...
by Tom Verhoeff 06 Nov '02

06 Nov '02

>Well, I have just been getting used to programming in Pascal again, and I thought I would write the age-old number guessing game. It all works, well it >*should* but I seem to be having problems with some logic in an if statement: > >if (iGuess > 0) or (iGuess < 101) then > { do my code } > >I thought this bit of code should detect if iGuess is inbetween 0 and 100, but >it doesn't seem to work! Can anyone tell me why? Your if-condition is True for any value of iGuess, because you use 'or' instead of 'and'! >Also is there a random number generator in gpc? I have hardcoded the value for >this program, I want to play with it being random too :) Yes, though I don't know the details. Tom

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mail tools released
by Frank Heckenbach 06 Nov '02

06 Nov '02

This is the announcement of the first public release of the mail tools. The mail tools are a set of programs to do various things with email, mostly in batch mode. The most important ones are `Semail' to send mails and `prmail' to process received mails (both written in GNU Pascal). The package also contains some generally useful units for GNU Pascal for sending and processing email, together with some demo programs, and some generally useful scripts related to mail handling. The mail tools are free software (GPL, LGPL). The current version of the mail tools can be found at <http://gnu-pascal.de/contrib/frank/programs.html>. Nicola Girardi Frank Heckenbach -- Frank Heckenbach, frank(a)g-n-u.de, http://fjf.gnu.de/, 7977168E GPC To-Do list, latest features, fixed bugs: http://www.gnu-pascal.de/todo.html GPC download signing key: 51FF C1F0 1A77 C6C2 4482 4DDC 117A 9773 7F88 1707

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Pointer type initializer
by Couperin 06 Nov '02

06 Nov '02

Hello, I tried to reduce a program I couldn''t compile. You'll see it below. I'm wondering if I made a mistake or if it's really a bug. I found that the problem comes from : P_Vecteur = ^T_Vecteur = Nil; (Everything is fine if I suppress the "= Nil".) In other programs, this declaration doesn't cause any problem, even if P_Vecteur is the argument of a procedure (and here there is no problem until the last procedure). Is it something I should avoid ? Here is the output of GPC : ./temp24_u2.pas: In procedure `Diffvecteurs': ./temp24_u2.pas:29: initial value is of wrong type gpc1.exe: c:/djgpp/bin/gpc.exe exited with status 1 or it may say also : ./temp24_u2.pas: In procedure `Diffvecteurs': ./temp24_u2.pas:29: incompatible types in initialization ./temp24_u2.pas:29: initial value is of wrong type gpc1.exe: c:/djgpp/bin/gpc.exe exited with status 1 and from time to time : Exiting due to signal SIGSEGV General Protection Fault at eip=00172911 ... (GNU Pascal v 2.1 alpha (20020910) with DJGPP, on WindowsME) ****************************** Program temp24; Uses temp24_u2; Begin End. ****************************** Unit temp24_u2; Interface Type P_Vecteur = ^T_Vecteur = Nil; T_Vecteur(N:Cardinal) = Array [1..N] Of LongReal; Implementation Procedure AddVecteurs(Resultat,A,B:P_Vecteur); Var Taille : Integer; Tampon : P_Vecteur; Procedure Addition(Resultat,AA,BB:P_Vecteur); Var I : Integer; Begin For I := 1 To Taille Do Resultat^[I] := AA^[I] + BB^[I] End; Begin End; Procedure DiffVecteurs(Resultat,A,B:P_Vecteur); Var Taille : Integer; Tampon : P_Vecteur; Procedure Soustraction(Resultat,AA,BB:P_Vecteur); Var K : Integer; Begin For K := 1 To Taille Do Resultat^[K] := AA^[K] - BB^[K] End; Begin End; Begin End. ****************************** -- "Couperin"

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Pascal bug?
by rossati＠libero.it 05 Nov '02

05 Nov '02

Vale The test on array of char seem not works for array of four char. Here there is a simple source, whit five test and where one is falling: program Prx; var a5: array[1..5] of char := '01960'; b5: array[1..5] of char := '01959'; a4: array[1..4] of char := '1960'; b4: array[1..4] of char := '1959'; as: string(4) := '1960'; bs: string(4) := '1959'; begin writeln('Test array of char'); if a5 <= '01959' then writeln('failed! array 5 - costant'); if a5 <= b5 then writeln('failed! array 5'); if a4 <= '1959' then writeln('failed! array 4 - costant'); {above the falling test?} if a4 <= b4 then writeln('failed! array 4'); if as <= bs then writeln('failed! string'); end. The work session is: C:\fsf\pascal>uname -a MS-DOS X6J0B4 8 00 pc C:\fsf\pascal>gpc -v Reading specs from c:/fsf/lib/gcc-lib/djgpp/2.952/specs gpc version 20001101, based on 2.95.2 19991024 (release) C:\fsf\pascal>gpc prx.pas C:\fsf\pascal>a Test array of char failed! array 4 C:\fsf\pascal> Best regards G. Rossati

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Re: GPC error messages
by Tom Schneider 05 Nov '02

05 Nov '02

Frank: > > Here is a bad chunk of code: > > > > ri := ri + > > end; > > > > This is what GPC has to say about it: > > > > ridi.p:1531: parse error before `End' > > > > Here is what the Sun Pascal compiler has to say about it: > > > > pc0: WorkShop Compilers 4.2 01/04/00 Pascal 4.2 patch 104632-11 > > Fri Nov 1 02:52:33 2002 ridi.p: > > 1531 end; > > E 18480----------------^--- Inserted identifier > > > > I always find the Sun display much easier to interpret instantly. It > > would be nice to have GPC show the line and show the point of the > > error. > > GPC's error messages (which follow the same standard as most GNU > programs) are more targeted towards automatic parsing. Yes, that's good. > If run call > GPC from a user interface that supports it (e.g., PENG ... excuse > the little plug ;-), Noted! > but I guess also RHIDE, Emacs, etc.), it will > show the source position. > > But if you prefer working on the command-line, here's a little > script to convert the message format. You have to pipe the error > messages through it, e.g. > > sh/bash: > > gpc <options> foo.pas 2>&1 | gnumsg2spc > > csh/tcsh: > > gpc <options> foo.pas |& gnumsg2spc > > DJGPP: > > redir -eo gpc <options> foo.pas | sh gnumsg2spc Thanks for the explanation. I was not able to locate gnumsg2spc on the web with google though. Where is it? > Another issue is that GPC's messages don't include the column > position. Unfortunately, that's hard to achieve with the current > design of the preprocessor and lexer. But a reimplementation of > those is planned, and then it will be possible I hope. Great! Tom Dr. Thomas D. Schneider National Cancer Institute Laboratory of Experimental and Computational Biology Frederick, Maryland 21702-1201 toms(a)ncifcrf.gov permanent email: toms(a)alum.mit.edu (use only if first address fails) http://www.lecb.ncifcrf.gov/~toms/

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GPC error messages
by toms＠ncifcrf.gov 01 Nov '02

01 Nov '02

Folks: Here is a bad chunk of code: ri := ri + end; This is what GPC has to say about it: ridi.p:1531: parse error before `End' Here is what the Sun Pascal compiler has to say about it: pc0: WorkShop Compilers 4.2 01/04/00 Pascal 4.2 patch 104632-11 Fri Nov 1 02:52:33 2002 ridi.p: 1531 end; E 18480----------------^--- Inserted identifier I always find the Sun display much easier to interpret instantly. It would be nice to have GPC show the line and show the point of the error. The Sun compiler is not supported and so will go away eventually and at that point I will rely on GPC so having strong diagnostics will help. Thanks, Tom Dr. Thomas D. Schneider National Cancer Institute Laboratory of Experimental and Computational Biology Frederick, Maryland 21702-1201 toms(a)ncifcrf.gov permanent email: toms(a)alum.mit.edu (use only if first address fails) http://www.lecb.ncifcrf.gov/~toms/

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Re: BUG? empty else
by da Silva, Joe 01 Nov '02

01 Nov '02

Agreed. This is not a bug. This reminds me of the "case" statement in Pascal 6000 (CDC). If you wanted to prevent a crash of your program, when an expression (variant-selector) was not matched by any case-constant-list, you HAD TO include an empty "otherwise" clause. BTW, when I reported this behaviour (ie. crash) as a bug, I was told that since a non-match was undefined, it was acceptable for the program to terminate with a run-time error (which is what it normally did). Joe. > -----Original Message----- > From: CBFalconer [SMTP:cbfalconer@yahoo.com] > Sent: Friday, November 01, 2002 2:35 AM > To: gpc(a)gnu.de > Subject: Re: BUG? empty else > > Eike Lange wrote: > > > > The following program compiles without warnings: > > > > { 2.1 (20020510), based on gcc-2.95.2 19991024 (release) } > > program bug; > > > > var > > i: Integer = 1; > > > > begin > > if i = 1 then > > WriteLn ('is 1') > > else if i = 2 then > > { do nothing } > > else > > { do nothing } > > end. > > Not a bug. Terrible program structure, leading to much confusion, > but valid. The null statement is specifically permitted. You > will often see such things as: > > WHILE whatever DO (* nothing *); > > With if/else if/else chains, a useful rule is to put the short > clauses first (if possible) and make the final else the longest > clause. i.e.: > > IF something THEN BEGIN > (* lots of code *) > END > ELSE BEGIN > (* a few lines *) > END; > > is inferior to: > > IF NOT something THEN BEGIN > (* a few lines *) > END > ELSE BEGIN > (* lots of code *) > END; > > for readability reasons. You can look up from any code and find > the controlling statement easily. This applies to most > languages. The compiler should normally be able to optimize away > any extra code generated. > > -- > Chuck F (cbfalconer(a)yahoo.com) (cbfalconer(a)worldnet.att.net) > Available for consulting/temporary embedded and systems. > <http://cbfalconer.home.att.net> USE worldnet address! > >

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Gpc November 2002