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Hello world program

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:

Table of contents
1 Line-oriented (aka Console)
1.1 ABC
1.2 Ada
1.3 AmigaE
1.4 APL
1.5 Assembly language
1.6 AWK
1.7 BASIC
1.8 BCPL
1.9 C
1.10 C++
1.11 C#
1.12 Clean
1.13 CLIST
1.14 COBOL
1.15 Common Lisp
1.16 Eiffel
1.17 Erlang
1.18 Forth
1.19 Fortran
1.20 Haskell
1.21 Iptscrae
1.22 Java
1.23 Logo
1.24 Lua
1.25 MIXAL
1.26 MSDOS batch
1.27 OCaml
1.28 OPL
1.29 Pascal
1.30 Perl
1.31 PHP
1.32 Pike
1.33 PL/I
1.34 Python
1.35 REXX, also NetRexx and Object REXX
1.36 Ruby
1.37 Sather
1.38 Scheme
1.39 sed (requires at least one line of input)
1.40 Self
1.41 Smalltalk
1.42 SML
1.43 SNOBOL
1.44 SQL
1.45 StarOffice Basic
1.46 Tcl
1.47 Turing
1.48 UNIX-style shell
1.49 Romanian pseudocode (UBB Cluj-Napoca)
2 Graphical User Interfaces - as traditional applications
3 Graphical User Interfaces - Web browser based
4 Document Formats
5 See also
6 External links

Line-oriented (aka Console)

ABC

WHILE (1=1) :

   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!"

Structured BASIC

   print "Hello, world!"

BCPL

   GET "LIBHDR"

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

C

   #include 

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

C++

   #include 
   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
   }

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

   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

   print "Hello, world!\\n"

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!' uppercase 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.'

StarOffice Basic

   sub main
   print "Hello, World"
   end sub

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 
   #include 
   #include 
   #include 
   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 
   #include 
   #include 
   #include 

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 

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.

   
   
   Hello World
   
   

HelloWorld Program says:

   
   

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.

      

Hello World Example

An easier method uses JavaScript implicitly, calling the reserved alert function. Cut and paste the following line inside the .... HTML tags.

    Hello World Example

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

   
   
   
   

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

   
   
   Hello, world!
   
   
   Hello, world!
   
   

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