Hello world

Demonstration compares C#, C++, and Rust "Hello World" programs

Each item in the IdiomsAndPatterns repository focues on a simple program construct built in each of the three languages: C++ 20, Rust 1.49, and C# 9.0. This may help you use what you know of C++ or C# (or Java) to learn Rust more easily.

We start here with the simplest programs in each of the three languagues.

Find instructions for downloading build chains for each of these languages in Tooling.

C++ hide

// Hello.cpp #include <iostream> int main() { std::cout << "\n Hello World from C++" << "\n\n"; }

C++ build and execute

cd build C:\...\HelloWorld\Cpp\build> cmake .. >NULL C:\...\HelloWorld\Cpp\build> cmake --build . >NULL C:\...\HelloWorld\Cpp\build> "./debug/HelloPrj.exe" Hello World from C++

CMakeLists.txt

# CMake HelloPrj - build C++ with CMake project(HelloPrj) set(CMake_CXX_STANDARD 20) # build HelloCMake.obj in folder # build/debug add_executable(HelloPrj Hello.cpp)

C++ Project Setup

Steps to create Project: - Create directory for project - Add source code file - Add CmakeLists.txt - CMakeDemo - mkdir build - cd build - cmake .. >NULL - cmake --build . >NULL - "./debug/PrjName.exe"

Rust unhide

// HelloWorld::main.rs fn main() { println!("Hello, world!"); }

Rust build and execute

C:\...\HelloWorld\Rust> cargo run -q Hello, world!

cargo.toml

[package] name = "rust" version = "0.1.0" authors = ["James W. Fawcett "] edition = "2018" [dependencies]

Rust Project Setup

Steps to create Project: - Issue command: cargo new PkgName - Edit cargo.toml to provide pkg_name in snake_case - cd src - Edit main.rs for project constent - cargo run -q

C# hide

using System; namespace HelloWorld { class Program { static void Main(string[] args) { Console.WriteLine("Hello World!"); } } }

C# build and execute

C:\...\HelloWorld\CSharp> dotnet run Hello World!

C# Project

C# Project Setup

Steps to create Project: - Issue command: dotnet new console - Edit Program.cs for project constent - dotnet run

4. Epilogue

The following pages provide sequences of code examples for idioms and principles in each of the three languages cited here, e.g. C#, C++, and Rust. Object model differences will often be pointed out in comments within the code blocks.