2014-04-26 10:52:28 -04:00
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quine
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2014-04-26 11:54:15 -04:00
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/kwi:n/ , n. [from the name of the logician Willard van Orman Quine, via
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Douglas Hofstadter] A program that generates a copy of its own source text
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as its complete output. Devising the shortest possible quine in some given
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programming language is a common hackish amusement. (We ignore some variants
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of BASIC in which a program consisting of a single empty string literal
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reproduces itself trivially.) Here is one classic quine: ((lambda (x) (list
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x (list (quote quote) x))) (quote (lambda (x) (list x (list (quote quote)
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x))))) This one works in LISP or Scheme. It's relatively easy to write
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quines in other languages such as Postscript which readily handle programs
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as data; much harder (and thus more challenging!) in languages like C which
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do not. Here is a classic C quine for ASCII machines: char*f=
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char*f=%c%s%c;main() {printf(f,34,f,34,10);}%c ;
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main(){printf(f,34,f,34,10);} For excruciatingly exact quinishness, remove
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the interior line breaks. Here is another elegant quine in ANSI C: #define
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q(k)main(){return!puts(#k \nq( #k ) );} q(#define q(k)main(){return!puts(#k
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\nq( #k ) );}) Some infamous Obfuscated C Contest entries have been quines
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that reproduced in exotic ways. There is an amusing Quine Home Page.
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