hello world program hello world redirects here for other uses see hello world disambiguation a hello world message being displayed through longexposure light painting with a moving strip of led lights a hello world program is a computer program that outputs or displays the message hello world because it is very simple in most programming languages it is often used to illustrate the basic syntax of a programming language and is often the first program people write purpose a hello world program is traditionally used to introduce novice programmers to a programming language hello world is also traditionally used in a sanity test to make sure that a computer language is correctly installed and that the operator understands how to use it history hello world program by brian kernighan 1978 while small test programs have 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 include stdioh main printfhello worldn the c version was preceded by kernighans own 1972 a tutorial introduction to the language b where the first known version of the program is found in an example used to illustrate external variables main extrn abc putchara putcharb putcharc putcharn a hell b o w c orld the program prints helloworld on the terminal including a newline character the phrase is divided into multiple variables because in b a character constant is limited to four ascii characters the previous example in the tutorial printed hi on the terminal and the phrase helloworld was introduced as a slightly longer greeting that required several character constants for its expression it is also claimed that for modern languages hello world programs vary in sophistication for example the go programming language introduced a multilingual program variations a hello world program running on sonys playstation portable as a proof of concept there are many variations on the punctuation and casing of the phrase variations include the presence or absence of the comma and exclamation mark and the capitalization of the h both the h and the w or neither some languages are forced to implement different forms such as hello world on systems that support only capital letters while many hello world programs in esoteric languages print out a slightly modified string for example the first nontrivial malbolge program printed hello world this having been determined to be good enough there are variations in spirit as well functional programming languages like lisp ml and haskell tend to substitute a factorial program for hello world as functional programming emphasizes recursive techniques whereas the original examples emphasize io which violates the spirit of pure functional programming by producing side effects languages otherwise capable of hello world assembly c vhdl may also be used in embedded systems where text output is either difficult requiring additional components or communication with another computer or nonexistent for devices such as microcontrollers fieldprogrammable gate arrays and cplds hello world may thus be substituted with a blinking led which demonstrates timing and interaction between components the debian and ubuntu linux distributions provide the hello world program through the apt packaging system this allows users to simply type aptget install hello for the program to be installed along with any software dependencies while of itself useless it serves as a sanity check and a simple example to newcomers of how to install a package it is significantly more useful for developers however as it provides an example of how to create a deb package either traditionally or using debhelper and the version of hello used gnu hello serves as an example of how to write a gnu program time to hello world time to hello world tthw is a metric for how long it takes to get a hello world program running from scratch 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