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".
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:
Line-oriented (aka Console)
WHILE (1=1) :
WRITE "Hello World "
with Ada.Text_Io; use Ada.Text_Io;
procedure Hello is
begin
Put_Line ("Hello, world!");
end Hello;
PROC main()
WriteF('Hello, World!')
ENDPROC
'Hello World'
DEC PDP-8, PAL-III syntax
See the Example section of the PDP-8 article.
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 AX, 4C00H
INT 21H
END
BEGIN { print "Hello, world!" }
MS BASIC (traditional, unstructured)
10 PRINT "Hello, world!" 20 END
:Disp "Hello, world!"
Structured BASIC
print "Hello, world!"
GET "LIBHDR"
LET START () BE
$(
WRITES ("Hello, world!*N")
$)
#include <stdio.h>
int main(void) {
printf("Hello, world!\n");
return 0;
}
#include <iostream> using namespace std;
int main() {
cout << "Hello, world!" << endl;
return 0;
}
class HelloWorldApp {
public static void Main() {
System.Console.WriteLine("Hello, world!");
}
}
module hello
Start :: String Start = "Hello, world"
PROC 0 WRITE Hello, World!
IDENTIFICATION DIVISION. PROGRAM-ID. HELLO-WORLD.
ENVIRONMENT DIVISION.
DATA DIVISION.
PROCEDURE DIVISION. DISPLAY "Hello, world!". STOP RUN.
(format t "Hello world!~%")
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
-module(hello).
-export([hello_world/0]).
hello_world() -> io:fwrite("Hello, world!\n").
." Hello, world!" CR
PROGRAM HELLO
WRITE(*,10)
10 FORMAT('Hello, world!')
STOP
END
module HelloWorld (main) where
main = putStr "Hello World\n"
ON ENTER {
"Hello, " "World!" & SAY
}
public class Hello {
public static void main(String[] args) {
System.out.println("Hello, world!");
}
}
print [hello world!]
print "Hello, world!"
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!
let _ =
print_endline "Hello world!";;
PROC hello:
PRINT "Hello, World"
ENDP
program Hello;
begin
writeln('Hello, world!');
end.
print "Hello, world!\n";
<?php
print("Hello, world!");
?>
#!/usr/local/bin/pike
int main() {
write("Hello, world!\n");
return 0;
}
Test: procedure options(main);
declare My_String char(20) varying initialize('Hello, world!');
put skip list(My_String);
end Test;
print "Hello, world!"
/* rexx */ say "Hello, world!"
print "Hello, world!\n"
class HELLO_WORLD is
main is
#OUT+"Hello World\n";
end;
end;
(display "Hello, world!") (newline)
sed (requires at least one line of input)
sed -ne '1s/.*/Hello, world!/p'
'Hello, World!' uppercase print.
Transcript show: 'Hello, world!'
print "Hello, world!\n";
OUTPUT = "Hello, world!" END
create table MESSAGE (TEXT char(15));
insert into MESSAGE (TEXT) values ('Hello, world!');
select TEXT from MESSAGE;
drop table MESSAGE;
sub main print "Hello, World" end sub
puts "Hello, world!"
put "Hello, world!"
echo 'Hello, world!'
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;
}
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();
}
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 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()
{
javascript: 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!')
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"> <box align="center"> <label value="Hello, world!" /> </box> </window>
Document Formats
- The following sequence of characters expressed in hexadecimal notation:
48 65 6C 6C 6F 2C 20 77 6F 72 6C 64 21 0D 0A
<HTML> <HEAD> <TITLE>Hello, world!</TITLE> </HEAD> <BODY> Hello, world! </BODY> </HTML>
/font /Courier findfont 24 scalefont font setfont 100 100 moveto (Hello world!) show showpage
\font\HW=cmr10 scaled 3000
\leftline{\HW Hello world}
\bye