#2 Hello, World!

Create a project

Cargo makes it easy to create a new Rust project. The cargo new command generates everything you need to get started:

$ cargo new hello-project
     Created binary (application) `hello-project` package

This creates a new directory called hello-project with a complete project structure, including a Git repository.

Project structure

Let's look at what Cargo generated:

hello-project/
├── Cargo.toml    # Project metadata and dependencies
└── src/
    └── main.rs   # Your Rust source code

Cargo.toml is the manifest file. It contains your project's name, version, and dependencies:

[package]
name = "hello-project"
version = "0.1.0"
edition = "2021"

[dependencies]

The main function

Every Rust program starts with a main function. Cargo generated a simple one for you in src/main.rs:

fn main() {
    println!("Hello, world!");
}

Let's break this down:

fn declares a function. main is the entry point of every Rust program. println! is a macro (notice the !) that prints text to the console with a newline at the end.

Build and run

To compile and run your project in one step, use cargo run:

$ cargo run
   Compiling hello-project v0.1.0 (/home/user/hello-project)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.42s
     Running `target/debug/hello-project`
Hello, world!

If you only want to compile without running, use cargo build. The compiled binary will be at target/debug/hello-project.

To quickly check your code compiles without producing a binary, use cargo check — it's faster than a full build.

Your turn

Try creating a project and running it. Use cargo new, cargo run, and cargo build in the terminal below: