Path: utzoo!mnetor!uunet!mcvax!prlb2!kulcs!luc
From: luc@kulcs.UUCP (Luc Van Braekel)
Newsgroups: comp.lang.pascal
Subject: Re: Self-replicating programs
Message-ID: <1092@kulcs.UUCP>
Date: 28 Dec 87 22:22:28 GMT
References: <52@qucis.UUCP> <188@goofy.megatest.UUCP>
Organization: Kath.Univ.Leuven, Comp. Sc., Belgium
Lines: 36
Summary: here is a machine-independant self-replicating pascal program

In article <188@goofy.megatest.UUCP>, djones@megatest.UUCP (Dave Jones) writes:
> The "quotemark" problem is the only hard problem. How do you make
> this program character-set independant?  (The one I posted will
> work just as well on an EBCDIC machine as on an ASCII machine.
> This posting does not contain everything I want ot know on
> self-replicating programs.
The quotemark problem is not so difficult to solve.  Here is a
slightly modified version of the program I posted some time ago.  This
version is character-set independant.  Again, this is an ugly but very
short Pascal program that doesn't use external files etc.  At least
one thing that's shorter in Pascal than in C ! :-)

program self (output);  const q = '''';                    
var i,j: integer;                                          
    a: array[1..8] of packed array[1..59] of char; begin   
  a[1] := 'program self (output);  const q = '''''''';                    ';
  a[2] := 'var i,j: integer;                                          ';
  a[3] := '    a: array[1..8] of packed array[1..59] of char; begin   ';
  a[4] := 'for i := 1 to 3 do writeln(a[i]);                          ';
  a[5] := 'for i := 1 to 8 do begin write(''  a['',i:0,''] := '',q);      ';
  a[6] := 'for j := 1 to 59 do begin write(a[i][j]);if a[i][j]=q      ';
  a[7] := 'then write(a[i][j]) end; writeln(q,'';'') end;               ';
  a[8] := 'for i := 4 to 8 do writeln(a[i]) end.                      ';
for i := 1 to 3 do writeln(a[i]);                          
for i := 1 to 8 do begin write('  a[',i:0,'] := ',q);      
for j := 1 to 59 do begin write(a[i][j]);if a[i][j]=q      
then write(a[i][j]) end; writeln(q,';') end;               
for i := 4 to 8 do writeln(a[i]) end.                      

+-----------------------------------+------------------------------------+
| Name   : Luc Van Braekel          |  Katholieke Universiteit Leuven    |
| UUCP   : luc@kulcs.UUCP           |  Department of Computer Science    |
| BITNET : luc@blekul60.bitnet      |  Celestijnenlaan 200 A             |
| Phone  : +(32) 16 20 0656 x3563   |  B-3030 Leuven (Heverlee)          |
| Telex  : 23674 kuleuv b           |  Belgium                           |
+-----------------------------------+------------------------------------+