Hello world program

Hello world is the name of a program that simply prints out "Hello world!".

This is a traditional first program to write when learning a new programming language, and can be a useful [sanity test]? to make sure that a language's [development environment]? and [run-time environment]? are correctly installed.

While minimal test programs such as this existed since the development of programmable computers, the tradition of using "Hello world!" as the test message was probably started by its use as an example program in the book The C Programming Language, by Brian Kernighan and Dennis Ritchie.

Here are some examples in different languages:

• Ada

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

• Assembly (x86 CPU, DOS, TASM syntax)

    MODEL SMALL
    IDEAL
    STACK 100H

    DATASEG
        HW      DB      'Hello, World!$'

    CODESEG
        MOV AX, @data
        MOV DS, AX
        MOV DX, OFFSET HW
        MOV AH, 09H
        INT 21H
        MOV AH, 4CH
        INT 21H
    END

• BASIC

    PRINT "Hello world!"

• Brainfuck

    >+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.[-]>++++++++[<++++>-]
    <.>+++++++++++[<++++++++>-]<-.- - - - - - - -.+++.- - - - - - . - - - - - - - -
    .[-]>++++++++[<++++>-]<+.[-]++++++++++.

• C

    #include <stdio.h>
    int main(void)
    {
        printf("Hello world!\n");
        return 0;
    }

• C++

    #include <iostream>
    int main()
    {
        std::cout << "Hello world!" << std::endl;
        return 0;
    }

• COBOL

    IDENTIFICATION DIVISION.
    PROGRAM-ID.     HELLO-WORLD.

    ENVIRONMENT DIVISION.

    DATA DIVISION.

    PROCEDURE DIVISION.
    DISPLAY "Hello, World".
    STOP RUN.

• Common Lisp

    (format t "Hello world!~%")

• Forth

    ." Hello world!" 10 EMIT

• INTERCAL

   PLEASE DO ,1 <- #13
   DO ,1 SUB #1 <- #238
   DO ,1 SUB #2 <- #112
   DO ,1 SUB #3 <- #112
   DO ,1 SUB #4 <- #0
   DO ,1 SUB #5 <- #64
   DO ,1 SUB #6 <- #238
   DO ,1 SUB #7 <- #26
   DO ,1 SUB #8 <- #248
   DO ,1 SUB #9 <- #168
   DO ,1 SUB #10 <- #24
   DO ,1 SUB #11 <- #16
   DO ,1 SUB #12 <- #158
   DO ,1 SUB #13 <- #52
   PLEASE READ OUT ,1
   PLEASE GIVE UP

• Java

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

• Java GUI

    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);
      }
    }

• Pascal

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

• Perl

    print "Hello world!\n"

• PHP3

    <?php
        echo "Hello world!\n";
    ?>

• 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!"

• Ruby (similarity to Perl version is not accidental)

    print "Hello world!\n"

• Smalltalk

    Transcript show: 'Hello world!'

• SQL

    SELECT 'Hello world!' FROM DUAL;

• Turing

    put "Hello world!"

Many more examples can be found at [Hello, World Page!].

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/Talk