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.
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 #%* polyglot@ideology.com.au *+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. *){*/}