Hello world program

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A "hello world" program is a computer program that simply prints out "Hello, world!". It is used in many introductory tutorials for teaching a programming language and many students use it as their first programming experience in a language. A "hello world" program is typically one of the simpler programs possible in a computer language. Some are surprisingly complex, especially in some Graphical User Interface (GUI) contexts. Some others are surprisingly simple, especially those which heavily rely on a particular shell to perform the actual output.

A "hello world" program can be a useful sanity test to make sure that a language's compiler, development environment, and run-time environment are correctly installed. Configuring a complete programming tool chain from scratch to the point where even trivial programs can be compiled and run may involve substantial amounts of work. For this reason, a simple program is used first when testing a new tool chain.

While small test programs existed since the development of programmable computers, the tradition of using the phrase "Hello, world!" as the test message was influenced by an example program in the book The C Programming Language, by Brian Kernighan and Dennis Ritchie. The example program from that book prints "hello, world" (i.e., no capital letters, no exclamation sign).

A collection of "hello world" programs written in various computer languages can serve as a simple "Rosetta Stone" to assist in learning and comparing the languages.

Here are some examples in different languages:

Contents

Line-oriented (aka Console)

ABC

WRITE "Hello World"

Ada 

   with Ada.Text_Io; use Ada.Text_Io;
   procedure Hello is
   begin
      Put_Line ("Hello, world!");
   end Hello;

AmigaE 

   PROC main()
      WriteF('Hello, World!')
   ENDPROC

APL 

   'Hello World'

Assembly language

Accumulator-only architecture: DEC PDP-8, PAL-III assembler

See the Example section of the PDP-8 article.

Accumulator + index register machine: MOS 6502, CBM, ca65 asm 

   MSG:   .ASCIIZ "Hello, world!"
           LDX    #0
           LDA    MSG,X    ; load initial char
   @LP:    JSR    $FFD2    ; CHROUT CBM KERNAL
           INX
           LDA    MSG,X
           BNE    @LP
           RTS

Accumulator/Index microcoded machine: Data General Nova, RDOS

See the example section of the Nova article.

Expanded accumulator machine: Intel x86, MS-DOS, TASM 

   MODEL   SMALL
   IDEAL
   STACK   100H

   DATASEG
           MSG DB 'Hello, world!$'

   CODESEG
           MOV AX, @data
           MOV DS, AX
           MOV DX, OFFSET MSG
           MOV AH, 09H      ; DOS: output ASCII$ string
           INT 21H
           MOV AX, 4C00H
           INT 21H
   END

General-purpose-register CISC: DEC PDP-11, RT-11, MACRO-11 

  .MCALL  .REGDEF,.TTYOUT,.EXIT
          .REGDEF

   HELLO:  MOV    #MSG,R1
           MOVB   (R1),R0
   LOOP:  .TTYOUT
           MOVB  +(R1),R0
           BNE    LOOP
          .EXIT

   MSG:   .ASCIZ  /HELLO, WORLD!/
          .END    HELLO

CISC: VAX, VMS, MACRO32 

        .title hello
term_name:      .ascid /SYS$INPUT/
term_chan:      .blkw 1
out_iosb:       .blkq 1
msg:    .asciz  /Hello, world!/

        .entry start,0

        ; establish a channel for terminal I/O
        $assign_s devnam=term_name,-
                chan=term_chan
        blbc r0,error

        ; queue the I/O request
        $qio_s chan=term_chan,-
                func=#io$_writevblk,-
                iosb=out_iosb,-
                p1=msg,-
                p2=#13
        blbc r0,error

        $exit_s ; normal exit

error:  halt ; error condition

       .end start

AWK 

   BEGIN { print "Hello, world!" }

BASIC

MS BASIC (traditional, unstructured)

   10 PRINT "Hello, world!"
   20 END

TI-BASIC 

   :Disp "Hello, world!"

StarOffice/OpenOffice Basic 

   sub main
       print "Hello, World"
   end sub

Structured BASIC 

   print "Hello, world!"

BCPL 

   GET "LIBHDR"

   LET START () BE
   $(
       WRITES ("Hello, world!*N")
   $)


C 

   #include <stdio.h>

   int main(void) {
       printf("Hello, world!\n");
       return 0;
   }

C++ 

   #include <iostream>
   using namespace std;

   int main() {
       cout << "Hello, world!" << endl;
       return 0;
   }

C# 

   class HelloWorldApp {
    public static void Main() {
       System.Console.WriteLine("Hello, world!");
    }
   }

Clean 

   module hello

   Start :: String
   Start = "Hello, world"

CLIST 

   PROC 0
   WRITE Hello, World!

COBOL 

   IDENTIFICATION DIVISION.
   PROGRAM-ID.     HELLO-WORLD.

   ENVIRONMENT DIVISION.

   DATA DIVISION.

   PROCEDURE DIVISION.
   DISPLAY "Hello, world!".
   STOP RUN.

Common Lisp 

   (format t "Hello world!~%")

Eiffel 

   class HELLO_WORLD

   creation
       make
   feature
       make is
       local
               io:BASIC_IO
       do
               !!io
               io.put_string("%N Hello, world!")
       end -- make
   end -- class HELLO_WORLD

Erlang 

       -module(hello).
       -export([hello_world/0]).

       hello_world() -> io:fwrite("Hello, world!\n").

Forth 

   ." Hello, world!" CR

Fortran 

      PROGRAM HELLO
      WRITE(*,10)
   10 FORMAT('Hello, world!')
      STOP
      END

Haskell 

   module HelloWorld (main) where

   main = putStr "Hello World\n"


Iptscrae 

   ON ENTER {
       "Hello, " "World!" & SAY
   }

Io 

   "Hello world!" print

or 

   write("Hello world!\n")

Java 

   public class Hello {
       public static void main(String[] args) {
           System.out.println("Hello, world!");
       }
   }

Logo 

   print [hello  world!]

Lua 

   print("Hello, world!")

MIXAL 

    TERM    EQU    19          the MIX console device number
            ORIG   1000        start address
    START   OUT    MSG(TERM)   output data at address MSG
            HLT                halt execution
    MSG     ALF    "MIXAL"
            ALF    " HELL"
            ALF    "O WOR"
            ALF    "LD   "
            END    START       end of the program

MSDOS batch 

   @echo off
   echo Hello, world!

OCaml 

   let _ =
      print_endline "Hello world!";;

OPL 

   PROC hello:
     PRINT "Hello, World"
   ENDP

Pascal 

   program Hello;
   begin
       writeln('Hello, world!');
   end.

Perl 

   print "Hello, world!\n";

PHP 

   <?php
       print("Hello, world!");
   ?>

Pike 

   #!/usr/local/bin/pike
   int main() {
       write("Hello, world!\n");
       return 0;
   }

PL/I 

   Test: procedure options(main);
      declare My_String char(20) varying initialize('Hello, world!');
      put skip list(My_String);
   end Test;

Python 

   print "Hello, world!"

REXX, also NetRexx and Object REXX 

   say "Hello, world!"

Ruby 

   puts "Hello, world!"

Sather 

   class HELLO_WORLD is
     main is 
      #OUT+"Hello World\n"; 
     end; 
   end;

Scheme 

   (display "Hello, world!")
   (newline)

sed (requires at least one line of input) 

   sed -ne '1s/.*/Hello, world!/p'

Self 

   'Hello, World!' print.

Smalltalk 

   Transcript show: 'Hello, world!'

SML 

   print "Hello, world!\n";

SNOBOL 

       OUTPUT = "Hello, world!"
   END

SQL 

   create table MESSAGE (TEXT char(15));
   insert into MESSAGE (TEXT) values ('Hello, world!');
   select TEXT from MESSAGE;
   drop table MESSAGE;

Or 

   select 'Hello, world' from dual;

Or, more simply 

   print 'Hello, World.'

Tcl 

   puts "Hello, world!"

Turing 

   put "Hello, world!"

UNIX-style shell 

   echo 'Hello, world!'

Romanian pseudocode (UBB Cluj-Napoca) 

   Algoritmul Salut este:
       fie s:="Hello, world";
       tipareste s;
   sf-Salut

Graphical User Interfaces - as traditional applications

C++ bindings for GTK graphics toolkit 

   #include <iostream>
   #include <gtkmm/main.h>
   #include <gtkmm/button.h>
   #include <gtkmm/window.h>
   using namespace std;

   class HelloWorld : public Gtk::Window {
   public:
     HelloWorld();
     virtual ~HelloWorld();
   protected:
     Gtk::Button m_button;
     virtual void on_button_clicked();

   };

   HelloWorld::HelloWorld()
   : m_button("Hello, world!") {
       set_border_width(10);
       m_button.signal_clicked().connect(SigC::slot(*this,
                                         &HelloWorld::on_button_clicked));
       add(m_button);
       m_button.show();
   }

   HelloWorld::~HelloWorld() {}

   void HelloWorld::on_button_clicked() {
       cout << "Hello, world!" << endl;
   }

   int main (int argc, char *argv[]) {
       Gtk::Main kit(argc, argv);
       HelloWorld helloworld;
       Gtk::Main::run(helloworld);
       return 0;
   }

Java 

   import java.awt.*;
   import java.awt.event.*;

   public class HelloFrame extends Frame {
     HelloFrame(String title) {
       super(title);
     }
     public void paint(Graphics g) {
       super.paint(g);
       java.awt.Insets ins = this.getInsets();
       g.drawString("Hello, world!", ins.left + 25, ins.top + 25);
     }
     public static void main(String args [])
     {
       HelloFrame fr = new HelloFrame("Hello");

       fr.addWindowListener(
         new WindowAdapter() {
           public void windowClosing(WindowEvent e)
           {
             System.exit( 0 );
           }
         }
       );
       fr.setResizable(true);
       fr.setSize(500, 100);
       fr.setVisible(true);
     }
   }


Qt toolkit (in C++) 

   #include <qapplication.h>
   #include <qpushbutton.h>
   #include <qwidget.h>
   #include <iostream>

   class HelloWorld : public QWidget
   {
       Q_OBJECT

   public:
       HelloWorld();
       virtual ~HelloWorld();
   public slots:
       void handleButtonClicked();
       QPushButton *mPushButton;
   };

   HelloWorld::HelloWorld() :
       QWidget(),
       mPushButton(new QPushButton("Hello, World!", this))
   {
       connect(mPushButton, SIGNAL(clicked()), this, SLOT(handleButtonClicked()));
   }

   HelloWorld::~HelloWorld() {}

   void HelloWorld::handleButtonClicked()
   {
       std::cout << "Hello, World!" << std::endl;
   }

   int main(int argc, char *argv[])
   {
       QApplication app(argc, argv);
       HelloWorld helloWorld;
       app.setMainWidget(&helloWorld);
       helloWorld.show();
       return app.exec();
   }

Visual Basic 

   MsgBox "Hello, world!"

Windows API (in C) 

   #include <windows.h>

   LRESULT CALLBACK WindowProcedure(HWND, UINT, WPARAM, LPARAM);

   char szClassName[] = "MainWnd";
   HINSTANCE hInstance;

   int WINAPI WinMain(HINSTANCE hInst, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
   {
     HWND hwnd;
     MSG msg;
     WNDCLASSEX wincl;

     hInstance = hInst;

     wincl.cbSize = sizeof(WNDCLASSEX);
     wincl.cbClsExtra = 0;
     wincl.cbWndExtra = 0;
     wincl.style = 0;
     wincl.hInstance = hInstance;
     wincl.lpszClassName = szClassName;
     wincl.lpszMenuName = NULL; //No menu
     wincl.lpfnWndProc = WindowProcedure;
     wincl.hbrBackground = (HBRUSH)(COLOR_WINDOW + 1); //Color of the window
     wincl.hIcon = LoadIcon(NULL, IDI_APPLICATION); //EXE icon
     wincl.hIconSm = LoadIcon(NULL, IDI_APPLICATION); //Small program icon
     wincl.hCursor = LoadCursor(NULL, IDC_ARROW); //Cursor

     if (!RegisterClassEx(&wincl))
           return 0;

     hwnd = CreateWindowEx(0, //No extended window styles
           szClassName, //Class name
           "", //Window caption
           WS_OVERLAPPEDWINDOW & ~WS_MAXIMIZEBOX,
           CW_USEDEFAULT, CW_USEDEFAULT, //Let Windows decide the left and top positions of the window
           120, 50, //Width and height of the window,
           NULL, NULL, hInstance, NULL);

     //Make the window visible on the screen
     ShowWindow(hwnd, nCmdShow);

     //Run the message loop
     while (GetMessage(&msg, NULL, 0, 0))
     {
           TranslateMessage(&msg);
           DispatchMessage(&msg);
     }
     return msg.wParam;
   }

   LRESULT CALLBACK WindowProcedure(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
   {
     PAINTSTRUCT ps;
     HDC hdc;
     switch (message)
     {
     case WM_PAINT:
           hdc = BeginPaint(hwnd, &ps);
           TextOut(hdc, 15, 3, "Hello, world!", 13);
           EndPaint(hwnd, &ps);
           break;
     case WM_DESTROY:
           PostQuitMessage(0);
           break;
     default:
           return DefWindowProc(hwnd, message, wParam, lParam);
     }
     return 0;
   }

Graphical User Interfaces - Web browser based

Java applet

Java applets work in conjunction with HTML files. 
   <HTML>
   <HEAD>
   <TITLE>Hello World</TITLE>
   </HEAD>
   <BODY>

   HelloWorld Program says:



   <APPLET CODE="HelloWorld.class" WIDTH=600 HEIGHT=100>
   </APPLET>

   </BODY>
   </HTML>

   import java.applet.*;
   import java.awt.*;

   public class HelloWorld extends Applet {
     public void paint(Graphics g) {
       g.drawString("Hello, world!", 100, 50);
     }
   }

JavaScript, aka ECMAScript

JavaScript is a scripting language used in HTML files. To demo this program Cut and Paste the following code into any HTML file. 
    <script language="javascript">
    function helloWorld()
    {
        alert("Hello, world!");
    }
    </script>  

    <a href="javascript:this.location()"
     onclick="javascript:helloWorld();">Hello World Example</a>
An easier method uses JavaScript implicitly, calling the reserved alert function. Cut and paste the following line inside the <BODY> .... </BODY> HTML tags. 
    <a href="#" onclick="alert('Hello, world!')">Hello World Example</a>
An even easier method involves using popular browsers' support for the virtual 'javascript' protocol to execute JavaScript code. Enter the following as an Internet address (usually by pasting into the address box): 
    javascript:alert('Hello, world!')

XUL 

   <window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
   <box align="center">
   <label value="Hello, world!" />
   </box>
   </window>

Document Formats

ASCII

The following sequence of characters, expressed in hexadecimal notation (with carriage return and newline characters at end of sequence): 

    48 65 6C 6C 6F 2C 20 77 6F 72 6C 64 21 0D 0A

HTML 

   <HTML>
   <HEAD>
   <TITLE>Hello, world!</TITLE>
   </HEAD>
   <BODY>
   Hello, world!
   </BODY>
   </HTML>

PostScript 

   /font /Courier findfont 24 scalefont
   font setfont
   100 100 moveto
   (Hello world!) show
   showpage

TeX 

   \font\HW=cmr10 scaled 3000
   \leftline{\HW Hello world}
   \bye

See also

External links


References

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