Hello World

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A Hello world program is a computer program that outputs ‘Hello, world’ on a display device. Because it is typically one of the simplest programs possible in most programming languages, it is by tradition often used to illustrate to beginners the most basic syntax of a programming language, or to verify that a language or system is operating correctly (called a sanity test). In a device that does not display text, a simple program to produce a signal, such as turning on an LED, is often substituted for ‘Hello world’ as the introductory program. Itis 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 (‘home brew’) on such a device.

While small test programs existed since the development of programmable computers, the tradition of using the phrase ‘Hello, world!’ as a test message was influenced by an example program in the seminal book ‘The C Programming Language.’ The example program from that book prints ‘hello, world’ (without capital letters or exclamation mark), and was inherited from a 1974 Bell Laboratories internal memorandum by Brian Kernighan, ‘Programming in C: A Tutorial.’

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