Polyglot (computing)
Encyclopedia
In computing
, a polyglot is a computer program
or script written in a valid form of multiple programming language
s, which performs the same operations or output independent of the programming language used to compile or interpret it.
Generally polyglots are written in a combination of C
(which allows redefinition of tokens with a preprocessor
) and a scripting language
such as Lisp, Perl
or sh
.
quirks. These are demonstrated in this public domain
polyglot written in ANSI C
, PHP
and bash:
#define a /*
# echo "\010Hello, world!\n";// 2> /dev/null > /dev/null \ ;
// 2> /dev/null; x=a;
$x=5; // 2> /dev/null \ ;
if (($x))
// 2> /dev/null; then
return 0;
// 2> /dev/null; fi
#define e ?>
#define b */
#include
#define main int main(void)
#define printf printf(
#define true )
#define function
function main
{
printf "Hello, world!\n"true/* 2> /dev/null | grep -v true*/;
return 0;
}
#define c /*
main
#*/
Note the following:
Some less-common languages also offer possibilities to create Polyglot code. Here is a small sample, written simultaneously in SNOBOL
4, Win32Forth, PureBasic
v4.x, and REBOL
:
*BUFFER : A.A ; .( Hello, world !) @ To Including?
Macro SkipThis; OUTPUT = Char(10) "Hello, World !"
;OneKeyInput Input('Char', 1, '[-f2-q1]') ; Char
End; SNOBOL4 + PureBASIC + Win32Forth + REBOL = <3
EndMacro: OpenConsole : PrintN("Hello, world !")
Repeat : Until Inkey : Macro SomeDummyMacroHere
REBOL [ Title: "'Hello, World !' in 4 languages"
CopyLeft: "Developed in 2010 by Society" ] Print
"Hello, world !" EndMacro: func [][] set-modes
system/ports/input [binary: true] Input set-modes
system/ports/input [binary: false] NOP:: EndMacro
; Wishing to refine it with new language ? Go on !
The term is sometimes applied to programs that are valid in more than one language, but do not strictly perform the same function in each. One use for this form is a file that runs as a DOS
batch file, then re-runs itself in Perl
:
@rem = ' --PERL--
@echo off
perl "%~dpnx0" %*
goto endofperl
@rem ';
#!perl
print "Hello, world!\n";
__END__
:endofperl
This allows creating Perl scripts that can be run on DOS systems with minimal effort.
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, a polyglot is a computer program
Computer program
A computer program is a sequence of instructions written to perform a specified task with a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute...
or script written in a valid form of multiple programming language
Programming language
A programming language is an artificial language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine and/or to express algorithms precisely....
s, which performs the same operations or output independent of the programming language used to compile or interpret it.
Generally polyglots are written in a combination of C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
(which allows redefinition of tokens with a preprocessor
Preprocessor
In computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers...
) and a scripting language
Scripting language
A scripting language, script language, or extension language is a programming language that allows control of one or more applications. "Scripts" are distinct from the core code of the application, as they are usually written in a different language and are often created or at least modified by the...
such as Lisp, Perl
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
or sh
Unix shell
A Unix shell is a command-line interpreter or shell that provides a traditional user interface for the Unix operating system and for Unix-like systems...
.
Methods
The two most commonly used techniques for constructing a polyglot program are to make liberal use of languages which use different characters for comments and to redefine various tokens as others in different languages. Often good use is made with syntaxSyntax
In linguistics, syntax is the study of the principles and rules for constructing phrases and sentences in natural languages....
quirks. These are demonstrated in this public domain
Public domain
Works are in the public domain if the intellectual property rights have expired, if the intellectual property rights are forfeited, or if they are not covered by intellectual property rights at all...
polyglot written in ANSI C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, PHP
PHP
PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...
and bash:
#define a /*
# echo "\010Hello, world!\n";// 2> /dev/null > /dev/null \ ;
// 2> /dev/null; x=a;
$x=5; // 2> /dev/null \ ;
if (($x))
// 2> /dev/null; then
return 0;
// 2> /dev/null; fi
#define e ?>
#define b */
#include
#define main int main(void)
#define printf printf(
#define true )
#define function
function main
{
printf "Hello, world!\n"true/* 2> /dev/null | grep -v true*/;
return 0;
}
#define c /*
main
#*/
Note the following:
- A hash sign marks a preprocessorPreprocessorIn computer science, a preprocessor is a program that processes its input data to produce output that is used as input to another program. The output is said to be a preprocessed form of the input data, which is often used by some subsequent programs like compilers...
statement in C, but is a comment in both bash and PHP. - "//" is a comment in both PHP and C++ and the root directoryRoot directoryIn computer file systems, the root directory is the first or top-most directory in a hierarchy. It can be likened to the root of a tree — the starting point where all branches originate.-Metaphor:...
in bash. - Shell redirection is used to eliminate undesirable outputs.
- Even on commented out lines, the "<?php" and "?>" PHP indicators still have effect.
- The statement "function main" is valid in both PHP and bash; C #defines are used to convert it into "int main" at compile time.
- Comment indicators can be combined to perform various operations.
- "if (($x))" is a valid statement in both bash and PHP.
- printf is a bash shell builtinShell builtinIn computing, a shell builtin is a command or a function, called from a shell, that is executed directly in the shell itself, instead of an external executable program which the shell would load and execute....
which is identical to the C printf except for its omission of brackets (which the C preprocessor adds if this is compiled with a C compiler). - The final three lines are only used by bash, to call the main function. In PHP the main function is defined but not called and in C there is no need to explicitly call the main function.
Some less-common languages also offer possibilities to create Polyglot code. Here is a small sample, written simultaneously in SNOBOL
SNOBOL
SNOBOL is a generic name for the computer programming languages developed between 1962 and 1967 at AT&T Bell Laboratories by David J. Farber, Ralph E. Griswold and Ivan P. Polonsky, culminating in SNOBOL4...
4, Win32Forth, PureBasic
PureBasic
PureBasic is a commercially distributed procedural computer programming language and integrated development environment based on BASIC and developed by Fantaisie Software for Windows 32/64-bit, Linux 32/64-bit, and Mac OS X. An Amiga version is available, although it has been discontinued and...
v4.x, and REBOL
REBOL
REBOL is a cross-platform data exchange language and a multi-paradigm dynamic programming language originally designed by Carl Sassenrath for network communications and distributed computing. The language and its official implementation, which is a proprietary freely redistributable software are...
:
*BUFFER : A.A ; .( Hello, world !) @ To Including?
Macro SkipThis; OUTPUT = Char(10) "Hello, World !"
;OneKeyInput Input('Char', 1, '[-f2-q1]') ; Char
End; SNOBOL4 + PureBASIC + Win32Forth + REBOL = <3
EndMacro: OpenConsole : PrintN("Hello, world !")
Repeat : Until Inkey : Macro SomeDummyMacroHere
REBOL [ Title: "'Hello, World !' in 4 languages"
CopyLeft: "Developed in 2010 by Society" ] Print
"Hello, world !" EndMacro: func [][] set-modes
system/ports/input [binary: true] Input set-modes
system/ports/input [binary: false] NOP:: EndMacro
; Wishing to refine it with new language ? Go on !
The term is sometimes applied to programs that are valid in more than one language, but do not strictly perform the same function in each. One use for this form is a file that runs as a DOS
DOS
DOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
batch file, then re-runs itself in Perl
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
:
@rem = ' --PERL--
@echo off
perl "%~dpnx0" %*
goto endofperl
@rem ';
#!perl
print "Hello, world!\n";
__END__
:endofperl
This allows creating Perl scripts that can be run on DOS systems with minimal effort.
External links
- An eight language polyglot (written in COBOLCOBOLCOBOL is one of the oldest programming languages. Its name is an acronym for COmmon Business-Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments....
, PascalPascal (programming language)Pascal is an influential imperative and procedural programming language, designed in 1968/9 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.A derivative known as Object Pascal...
, FortranFortranFortran is a general-purpose, procedural, imperative programming language that is especially suited to numeric computation and scientific computing...
, CC (programming language)C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, PostScriptPostScriptPostScript is a dynamically typed concatenative programming language created by John Warnock and Charles Geschke in 1982. It is best known for its use as a page description language in the electronic and desktop publishing areas. Adobe PostScript 3 is also the worldwide printing and imaging...
, Unix shellUnix shellA Unix shell is a command-line interpreter or shell that provides a traditional user interface for the Unix operating system and for Unix-like systems...
, Intel x86 machine language and PerlPerlPerl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
5) - A six language polyglot (written in PerlPerlPerl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
, CC (programming language)C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
, Unix shellUnix shellA Unix shell is a command-line interpreter or shell that provides a traditional user interface for the Unix operating system and for Unix-like systems...
, BrainfuckBrainfuckThe brainfuck programming language is an esoteric programming language noted for its extreme minimalism. It is a Turing tarpit, designed to challenge and amuse programmers, and is not suitable for practical use...
, WhitespaceWhitespace (programming language)Whitespace is an esoteric programming language developed by Edwin Brady and Chris Morris at the University of Durham . It was released on 1 April 2003 . Its name is a reference to whitespace characters...
and BefungeBefungeBefunge is a stack-based, reflective, esoteric programming language. It differs from conventional languages in that programs are arranged on a two-dimensional grid...
) - List of generic polyglots
- Merry Christmas polyglot in 4 languages
- Happy New year polyglot in 4 languages
- Computer polyglot in ANSI CANSI CANSI C refers to the family of successive standards published by the American National Standards Institute for the C programming language. Software developers writing in C are encouraged to conform to the standards, as doing so aids portability between compilers.-History and outlook:The first...
, Unix shellUnix shellA Unix shell is a command-line interpreter or shell that provides a traditional user interface for the Unix operating system and for Unix-like systems...
, PerlPerlPerl is a high-level, general-purpose, interpreted, dynamic programming language. Perl was originally developed by Larry Wall in 1987 as a general-purpose Unix scripting language to make report processing easier. Since then, it has undergone many changes and revisions and become widely popular...
and TclTclTcl is a scripting language created by John Ousterhout. Originally "born out of frustration", according to the author, with programmers devising their own languages intended to be embedded into applications, Tcl gained acceptance on its own... - A polyglot in 16 different languages