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From: hansm@cs.kun.nl (Hans Mulder)
Newsgroups: comp.lang.perl
Subject: Re: Self-reproducing program
Message-ID: <2901@wn1.sci.kun.nl>
Date: 27 Mar 91 20:04:51 GMT
References: <1991Mar26.210348.12286@uvaarpa.Virginia.EDU>
Sender: root@sci.kun.nl
Organization: University of Nijmegen, The Netherlands
Lines: 43

In article <1991Mar26.210348.12286@uvaarpa.Virginia.EDU> worley@compass.com writes:
>I don't know if this has been hashed over before, but: What is the
>shortest self-reproducing Perl program?  (Well, the null file is, but
>what is the shortest non-trivial program?)
>
>The best I've been able to do is:
>
>print @a=<DATA>,@a
>__END__
>print @a=<DATA>,@a
>__END__

Last time we had this debate, several shorter scripts were posted:

The first example is a 3-liner; the third line being empty:

print<<''x 2,$/
print<<''x 2,$/


The ohter four examples do not contain newlines; according to wc(1),
they are 0-liners:

This one assumes ascii, to the extent that ord("'")==39:

$s='$s=%c%s%c;printf$s,39,$s,39';printf$s,39,$s,39

This one does not unduly assume anything:

$_=q $_=qx;s/x/$"$_$"/;print ;s/x/$"$_$"/;print

The whitespace in this one must be tabs:

$_=q	print"\$_=q\t$_\t;eval"	;eval

This one again uses "\47" eq "'":

$_='print"\$_=\47$_\47;eval"';eval


Have a nice day,

Hans Mulder	hansm@cs.kun.nl