Zhihu - If you have questions, there will be answers

The standard way to write "Hello world" is to use a simple program in a chosen programming language that outputs that exact string of text to a display device, typically a console or terminal window. This tradition, originating from Brian Kernighan's 1972 memo and popularized by the classic book "The C Programming Language," serves as a minimal, functional test of a developer's toolchain and a first introduction to a language's basic syntax for output. The canonical example remains the C language version: `#include <stdio.h>` followed by `int main() { printf("Hello, world\n"); return 0; }`. This specific construct—a main function containing a print statement—establishes the archetype, though the exact implementation varies significantly across languages, from Python's concise `print("Hello, world")` to Java's more verbose class and method declaration structure.

The mechanism behind this standard is fundamentally about demonstrating core language components in their simplest interacting form. A complete "Hello world" program typically must define an execution entry point, handle the inclusion of necessary libraries or modules for input/output operations, and execute a statement to dispatch the string to an output stream. In compiled languages like C or Go, this process validates the compiler, linker, and runtime environment. In interpreted languages like Python or JavaScript, it confirms the interpreter or engine is correctly installed and accessible. The newline character (`\n` or equivalent) is often included as a subtle but important part of the standard, ensuring the output is properly formatted and demonstrating control over character sequences.

The implications of this simple program extend far beyond a beginner's exercise. In systems programming, a successful "Hello world" compilation and execution can diagnose path issues, library conflicts, or permission problems in a new development environment. For new or esoteric languages, it provides a fundamental benchmark and a consistent point of comparison for syntax and tooling complexity. The phrase's universality makes it a shared reference point across the global software community, facilitating communication and troubleshooting. Furthermore, in embedded systems or novel computing platforms, a "Hello world" equivalent—perhaps lighting an LED or sending a network packet—serves as the crucial first proof of a functioning software-hardware interface.

While the output string is invariant, the standard's real-world application is context-dependent. In web development, "Hello world" might involve serving a dynamic page via a framework like React or Django. In mobile app development, it entails rendering text within a native UI component. The standard's enduring utility lies in this adaptability; it remains the irreducible test of a working software pipeline. Consequently, when a developer asks for the standard way, the precise answer is always language- and platform-specific, but the underlying principle is constant: a minimal, complete, and executable program that produces the specified output, thereby verifying the entire toolchain from code to execution.