Project Structure

What is Cargo?

Cargo is Rust's build system and package manager which streamlines almost every aspect of your Rust workflow:

• Project Creation: cargo new quickly sets up a new Rust project with the correct structure.
• Building: cargo build compiles your code into an executable program.
• Running: cargo run builds and then executes your program.
• Testing: cargo test runs your project's tests.

Let's create our classic "Hello, world!" program using Cargo.

1. Create a New Project:
   • In your terminal, navigate to a directory where you want to create your project (e.g., your Desktop or a dev folder).
   • Run this command:

     cargo new hello_rust_app

   • Cargo will create a new folder named hello_rust_app with a basic project structure inside.
2. Explore the Project Structure:
   • Navigate into the new folder: cd hello_rust_app
   • Look at the contents:
     • Cargo.toml: This is the manifest file for your project. It contains metadata about your project (name, version) and lists its dependencies.
     • src/main.rs: This is where your main Rust code lives.
     • target/: (Created after you build) This is where compiled executable files go.
3. Examine src/main.rs:
   • Open src/main.rs in your VS Code. You'll see:

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

     • fn main(): This is the main function, the entry point of every Rust executable program.
     • println!: This is a macro (indicated by the !). It prints text to the console.
4. Run Your Application:
   • In your terminal (make sure you're inside the hello_rust_app folder), run:

     cargo run

   • What happens?
     • Cargo first compiles your code (you'll see messages like "Compiling hello_rust_app v0.1.0...").
     • Then, it executes the compiled program.
   • You should see: Hello, world! printed in your terminal.

Congratulations! You've just created and run your very first Rust application.