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"Hello World" redirects here. For the 2009 compilation album by Michael Jackson, see Hello World: The Motown Solo Collection. For the song by Lady Antebellum, see Hello World (song).
A GUI "Hello World" program, written in Perl
Hackers can execute unsigned code on Sony's PlayStation Portable.
A light-programmable biofilm displaying the Hello World message
CNC machining test in Perspex
A "Hello world" program is a computer program that prints out "Hello world" on a display device. It is typically one of the simplest programs possible in most programming languages. Therefore, by tradition, it is often the first program taught in a beginning class on a particular language. It is also used to illustrate the most basic syntax of a programming language.
Most of these programs are very simple, especially those that rely on a command-line interpreter (shell) to perform the actual output. However, they can be surprisingly complex, especially when writing the program for graphical user interface.
When programming an embedded system, the text may be sent to a liquid crystal display. In a device that does not display text, a simple program to produce a signal, such as turning on an LED, may be substituted for "Hello world" as the introductory program.
Contents
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* 1 Purpose
* 2 History
* 3 Variations
* 4 See also
* 5 References
* 6 External links
[edit] Purpose
A "hello world" program has become the traditional first program that many people learn. In general, it is simple enough that people who have no previous experience with computer programming can easily understand it, especially with the guidance of a teacher or a written guide. Using this simple program as a basis, computer science principles or elements of a specific programming language can be explained to novice programmers. Experienced programmers learning new languages can also gain a lot of information about a given language's syntax and structure from a hello world program.
In addition, hello world 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 toolchain from scratch to the point where even trivial programs can be compiled and run can involve substantial amounts of work. For this reason, a simple program is used first when testing a new tool chain.
"Hello world" is also used by computer hackers as a proof of concept that arbitrary code can be executed through an exploit where the system designers did not intend code to be executed—for example, on Sony's PlayStation Portable. This is the first step in using homemade content ("homebrew") on such a device.
