Setting Up and Hello World

Getting started with Rust is straightforward thanks to rustup, the official Rust toolchain installer. This lesson covers installation, your first program, and an introduction to Cargo.

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Installing Rust with rustup

The recommended way to install Rust is via rustup, which manages Rust versions and associated tools:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

After installation, verify:

rustc --version
cargo --version

What rustup Installs

Component	Description
rustc	The Rust compiler
cargo	Build system and package manager
rustfmt	Code formatter
clippy	Linter
rust-docs	Offline documentation
rust-std	Standard library

Managing Toolchains

# Update Rust to the latest stable version
rustup update

# Install the nightly toolchain
rustup install nightly

# Set the default toolchain
rustup default stable

# Show installed toolchains
rustup show

Rust has three release channels: stable (every 6 weeks), beta, and nightly.

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Your First Rust Program

Create a file called main.rs:

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

Compile and run it:

rustc main.rs
./main
# Output: Hello, world!

Key Observations

• fn main() — the entry point of every Rust program
• println! — a macro (note the !) that prints to standard output
• Semicolons — statements end with ;
• Curly braces — Rust uses {} for blocks, not indentation

Tip: The ! in println! means it is a macro, not a function. Macros can accept a variable number of arguments and generate code at compile time.

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Introduction to Cargo

While rustc compiles single files, Cargo is the standard tool for real Rust projects:

# Create a new project
cargo new hello_cargo
cd hello_cargo

# Build the project
cargo build

# Build and run in one step
cargo run

# Check for errors without producing a binary
cargo check

# Build with optimisations for release
cargo build --release

Project Structure

hello_cargo/
├── Cargo.toml    # Project manifest (dependencies, metadata)
├── Cargo.lock    # Exact dependency versions (auto-generated)
└── src/
    └── main.rs   # Main source file

Cargo.toml

The project manifest:

[package]
name = "hello_cargo"
version = "0.1.0"
edition = "2021"

[dependencies]
# Add crates from crates.io here