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Programming-Idioms

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  • Perl

Idiom #182 Quine program

Output the source of the current program. A quine is a computer program that takes no input and produces a copy of its own source code as its only output.

Reading the source file from disk is cheating.

$_=q(print"\$_=q($_);eval;");eval;

Assigns a string with valid Perl code and then evaluates it. Original author unknown, probably dates back to Usenet days.
int main(){char*s="int main(){char*s=%c%s%c;printf(s,34,s,34);return 0;}";printf(s,34,s,34);return 0;}
New implementation...
< > ⌨
a 
$_=q(print"\$_=q($_);eval;");eval;
int main(){char*s="int main(){char*s=%c%s%c;printf(s,34,s,34);return 0;}";printf(s,34,s,34);return 0;}
main(p){printf(p="main(p){printf(p=%c%s%1$c,34,p);}",34,p);}
public class Quine{public static void Main(){var s="public class Quine{{public static void Main(){{var s={0}{1}{0};System.Console.Write(s,(char)34,s);}}}}";System.Console.Write(s,(char)34,s);}}
q=<<"q=~p;:io.format q,[q]">>;:io.format q,[q]
! See original attribution URL
package main

import "fmt"

func main() {
	fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60)
}

var s = `package main

import "fmt"

func main() {
	fmt.Printf("%s%c%s%c\n", s, 0x60, s, 0x60)
}

var s = `
main = putStr s >> print s where s = "main = putStr s >> print s where s = "
c=console.log
q=decodeURIComponent('%22')
l=[
"c=console.log",
"q=decodeURIComponent('%22')",
"l=[",
"]",
"for(i=0;i<3;i++)c(l[i])",
"for(i=0;i<7;i++)c(q+l[i]+q+',')",
"for(i=3;i<7;i++)c(l[i])",
]
for(i=0;i<3;i++)c(l[i])
for(i=0;i<7;i++)c(q+l[i]+q+',')
for(i=3;i<7;i++)c(l[i])

x = [["x = [" .. "[" .. x .. "]" .. "]\nprint(" .. x)]]
print("x = [" .. "[" .. x .. "]" .. "]\nprint(" .. x)
<?php $s='<?php $s=%c%s%c;printf($s,39,$s,39);';printf($s,39,$s,39);
program Quine(Output);const A='program Quine(Output);const A=';B='begin writeln(A,char(39),A,char(39),char(59),char(66),char(61),char(39),B,char(39),char(59),B)end.';begin writeln(A,char(39),A,char(39),char(59),char(66),char(61),char(39),B,char(39),char(59),B)end.
s = 's = %r\nprint(s%%s)'
print(s%s)
eval s="print 'eval s=';p s"
fn main(){print!("{},{0:?})}}","fn main(){print!(\"{},{0:?})}}\"")}
fn main() {
    let x = "fn main() {\n    let x = ";
    let y = "print!(\"{}{:?};\n    let y = {:?};\n    {}\", x, x, y, y)\n}\n";
    print!("{}{:?};
    let y = {:?};
    {}", x, x, y, y)
}
object Quine extends App {
  val s = 
    """object Quine extends App {
      |  val s = 
      |    ""%2$s%1$s%2$s""
      |  print(s.stripMargin.format(s, "\""))
      |}"""
  print(s.stripMargin.format(s, "\""))
}
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