What's the most complex/powerful code you can write that's valid in a maximum number of languages?
So, for example, the following code is valid in both PHP and JavaScript.
function foo($bar)
{
$var = 0;
for($i=0;$i<100;$i++)
{
$var += ($bar + 2)/(1+$i);
}
return $var;
}
Why is this a useful challenge? I think its a useful way to think about how similar languages can be, and how easily knowing one's syntax can translate into learning another's.
(Where did the 'Community wiki' option go...?)
This is called a Polyglot, and it can get very complex. Here's one in eight languages: http://ideology.com.au/polyglot/
Cobol, Pascal, Fortran, C, PostScript, bash, x86 machine language, and Perl:
(*O/*_/
Cu #%* )pop mark/CuG 4 def/# 2 def%%%%@@P[TX---P\P_SXPY!Ex(mx2ex("SX!Ex4P)Ex=
CuG #%* *+Ex=
CuG #%*------------------------------------------------------------------*+Ex=
CuG #%* POLYGLOT - a program in eight languages 15 February 1991 *+Ex=
CuG #%* 10th Anniversary Edition 1 December 2001 *+Ex=
CuG #%* *+Ex=
CuG #%* Written by Kevin Bungard, Peter Lisle, and Chris Tham *+Ex=
CuG #%* *+Ex=
CuG #%* Polyglot suports the following languages: *+Ex=
CuG #%* 1. COBOL (ANSI) *+Ex=
CuG #%* 2. Pascal (ISO) *+Ex=
CuG #%* 3. Fortran (ANSI, f77) *+Ex=
CuG #%* 4. C (ANSI-ish) *+Ex=
CuG #%* 5. PostScript *+Ex=
CuG #%* 6. Linux/Unix shell script (bash, sh, csh) *+Ex=
CuG #%* 7. x86 machine language (MS-DOS, Win32, Linux) *+Ex=
CuG #%* 8. Perl (version 5) *+Ex=
CuG #%* *+Ex=
CuG #%* Usage: *+Ex=
CuG #%* 1. Rename this file to polyglot.[cob|pas|f77|c|ps|sh|com|pl] *+Ex=
CuG #%* *+Ex=
CuG #%* 2. Compile and run with your favorite compiler and operating *+Ex=
CuG #%* system. *+Ex=
CuG #%* *+Ex=
CuG #%* Notes: *+Ex=
CuG #%* 1. We have attempted to use only standard language features. *+Ex=
CuG #%* *+Ex=
CuG #%* 2. Without the -traditional flag gcc will issue a warning. *+Ex=
CuG #%* *+Ex=
CuG #%* 3. When transferring from Unix to DOS make sure that a LF *+Ex=
CuG #%* is correctly translated into a CR/LF. *+Ex=
CuG #%* *+Ex=
CuG #%* 4. Keep the blank lines at the start of the program. They *+Ex=
CuG #%* are important. *+Ex=
CuG #%* *+Ex=
CuG #%* 5. This text is a comment block in all eight languages. *+Ex=
CuG #%* *+Ex=
CuG #%* Please mail any comments, corrections or additions to *+Ex=
CuG #%* [email protected] *+Ex=
CuG #%* *+Ex=
CuG #%*------------------------------------------------------------------*QuZ=
CuG #%* *+Ex=
CuG #%*!Mx)ExQX5ZZ5SSP5n*5X!)Ex+ExPQXH,B+ExP[-9A-9B(g?(gA'UTTER_XYZZXX!X *+
CuG #(* *(
C # */); /*(
C # *) program polyglot (output); (*+
C # identification division.
C # program-id. polyglot.
C #
C # data division.
C # procedure division.
C #
C # * ))cleartomark /Bookman-Demi findfont 36 scalefont setfont (
C # * (
C #
C # * hello polyglots$
C # main.
C # perform
C /# * ) 2>_$$; echo "hello polyglots"; rm _$$; exit;
C # * (
C #
C *0 ) unless print "hello polyglots\n"; __END__
print
C stop run.
-*, 'hello polyglots'
C
C print.
C display "hello polyglots". (
C */ int i; /*
C */ main () { /*
C */ i=printf ("hello polyglots\n"); O= &i; return *O; /*
C *) (*
C *) begin (*
C *) writeln ('hello polyglots'); (*
C *) (* )
C * ) pop 60 360 (
C * ) pop moveto (hello polyglots) show (
C * ) pop showpage ((
C *)
end .(* )
C)pop% program polyglot. *){*/}