Hello World
Melva Simons
A "Hello, World!" program is generally a simple computer program which outputs (or displays) to the screen (often the console) a message similar to "Hello, World!" while ignoring any user input. A small piece of code in most general-purpose programming languages, this program is used to illustrate a language's basic syntax. A "Hello, World!" program is often the first written by a student of a new programming language,[1] but such a program can also be used as a sanity check to ensure that the computer software intended to compile or run source code is correctly installed, and that its operator understands how to use it.
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 1978 book The C Programming Language,[2] with likely earlier use in BCPL. The example program from the book prints "hello, world", and was inherited from a 1974 Bell Laboratories internal memorandum by Brian Kernighan, Programming in C: A Tutorial:[3]
In the above example, the main( ) function defines where the program should start executing. The function body consists of a single statement, a call to the printf() function, which stands for "print formatted"; it outputs to the console whatever is passed to it as the parameter, in this case the string "hello, world".
The C-language version was preceded by Kernighan's own 1972 A Tutorial Introduction to the Language B,[4] where the first known version of the program is found in an example used to illustrate external variables:
The program above prints hello, world! 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 hello, world! was introduced as a slightly longer greeting that required several character constants for its expression.
The Jargon File reports that "hello, world" instead originated in 1967 with the language BCPL.[5] Outside computing, use of the exact phrase began over a decade prior; it was the catchphrase of New York radio disc jockey William B. Williams beginning in the 1950s.[6]
"Hello, World!" programs vary in complexity between different languages. In some languages, particularly scripting languages, the "Hello, World!" program can be written as a single statement, while in others (particularly many low-level languages) there can be many more statements required. For example, in Python, to print the string Hello, World! followed by a newline, one only needs to write print("Hello, World!"). In contrast, the equivalent code in C++[7] requires the import of the input/output software library, the manual declaration of an entry point, and the explicit instruction that the output string should be sent to the standard output stream.
The phrase "Hello, World!" has seen various deviations in casing and punctuation, such as the capitalization of the leading H and W, and the presence of the comma or exclamation mark. Some devices limit the format to specific variations, such as all-capitalized versions on systems that support only capital letters, while some esoteric programming languages may have to print a slightly modified string. For example, the first non-trivial Malbolge program printed "HEllO WORld", this having been determined to be good enough.[8][unreliable source?] Other human languages have been used as the output; for example, a tutorial for the Go programming language outputted both English and Chinese or Japanese characters, demonstrating the programming language's built-in Unicode support.[9] Another notable example is the Rust programming language, whose management system automatically inserts a "Hello, World" program when creating new projects.
Some languages change the functionality of the "Hello, World!" program while maintaining the spirit of demonstrating a simple example. Functional programming languages, such as Lisp, ML, and Haskell, tend to substitute a factorial program for "Hello, World!", as functional programming emphasizes recursive techniques, whereas the original examples emphasize I/O, which violates the spirit of pure functional programming by producing side effects. Languages otherwise capable of printing "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, field-programmable gate arrays, and CPLDs, "Hello, World!" may thus be substituted with a blinking LED, which demonstrates timing and interaction between components.[10][11][12][13][14]
The Debian and Ubuntu Linux distributions provide the "Hello, World!" program through their software package manager systems, which can be invoked with the command hello. It serves as a sanity check and a simple example of installing a software package. For developers, it provides an example of creating a .deb package, either traditionally or using debhelper, and the version of hello used, GNU Hello, serves as an example of writing a GNU program.[15]
Variations of the "Hello, World!" program that produce a graphical output (as opposed to text output) have also been shown. Sun demonstrated a "Hello, World!" program in Java based on scalable vector graphics,[16] and the XL programming language features a spinning Earth "Hello, World!" using 3D computer graphics.[17] Mark Guzdial and Elliot Soloway have suggested that the "hello, world" test message may be outdated now that graphics and sound can be manipulated as easily as text.[18]
"Time to hello world" (TTHW) is the time it takes to author a "Hello, World!" program in a given programming language. This is one measure of a programming language's ease of use; since the program is meant as an introduction for people unfamiliar with the language, a more complex "Hello, World!" program may indicate that the programming language is less approachable.[19] The concept has been extended beyond programming languages to APIs, as a measure of how simple it is for a new developer to get a basic example working; a shorter time indicates an easier API for developers to adopt.[20][21]
In Computer Science 101, the first program many students create is a simple one that outputs an iconic line of text: "Hello World!" Say hello to the world of computer science with this introductory activity that equips students with the basic coding skills and confidence to create apps. Choose from six fun themes to code interactive characters in a world you create!
Hello World is the perfect first step for classrooms before trying the open-ended projects within our new curriculum, CS Connections! After learning some coding basics, students will be able to progress to CS Connections' cross-curricular projects.
Like when you go into a coffee shop or
restaurant, and everyone is sitting alone.
The tables all empty out as soon as you walk in.
If you sit down at an empty table, someone
will come over to talk to you, but
no one wants to sit next to you.
No. He or she must be someone who lives their daily life by
interacting with others. This person needs to be someone
who gets caught up in his or her own thoughts. Someone
who wants to change the world.
The protagonist has always been angry at his father. When
he was younger, he tried to stop his father from cheating
on his mother by stabbing him. However, his father
survived and took him to court. In the end, the
judge ruled that the protagonist could stay with
his father. This made him angrier than ever.
It is an emptiness which must be filled by thoughts.
Thoughts cannot exist without a vessel for them. And
if there is nothing else, then those thoughts will
become pure emptiness. The only way to fill such
emptiness is through another person who exists
within the same space as you. So even though
I am not a physical being, I am still human.
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IIRC, Go also uses a static linking approach for the sake of easier deployment, and in this sense would compare a little better to Rust than Java, whose idiomatic compilation model requires separate installation of the JVM. But indeed, it does have a lot more runtime black magic under the hood.
You also have to remember that Go wrote their own toolchain (compiler + assembler + linker) and they don't link to any kind of libc (they use the underlying syscalls directly). I'm assuming that extra control over the toolchain and less system dependencies would mean they can skip a lot of the extra baggage that a statically linked Rust or C program would have.
I guess this is one of the very few areas where Rust build toolchains could learn from CMake: there are three important build configurations, not two, and these are Debug, Release, and RelWithDebInfo.
The problem is specific to the standard library: in Rust, stdlib is distributed with the compiler in compiled form, as an rlib, so the end application compilation flags do not affect it. Moreover, the same rlib is used for both the release and debug profiles, and it is compiled with precisely release with debuginfo configuration
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