Hello world

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

rustc

• rustc FILE_NAME.rs
  • create a new compiled binary with same filename without rs extention

Cargo

• cargo build
  • cargo build --release
• cargo run
• cargo check
• cargo update
  • update dependencies

Comments

• //

Functions

Associated functions

• An associated function is a function that’s implemented on a type.
  • Invoked like this String::new()

Variables

// without type annotation
let cars = 2;

// with type annotation
let cars: i32 = 2;

// multiple variables
let (cars, trucks) = (2,4);

• by default variables are immutable
  • reason safety, concurrency and speed
    • lot of bugs cannot happen if value is not changed, hence safety improved
    • data shared between threads and processes does not change and required less locks, hence concurrency is improved
    • compiler can do compile time optimization if it knows data does not change, he speed of application is improved

// make variable mutable by adding 'mut' keyword before variable name
let mut cars = 2;

const

const PI: f64: 3.14

• const keyword is used to define constant variable which can be used across module scope, which is defined outside the functions
• shake case is the convention for const variable name
• inline to compiple time, they are fast to access in program.