dumindu

struct Color (u8, u8, u8);
struct Kilometers(i32);

fn main() {
  // creating an instance
  let black = Color (0, 0, 0);
  
  // destructure the instance using a `let` binding, this will not destruct black instance
  let Color (r, g, b) = black;
  println!("Black = rgb({}, {}, {})", r, g, b); //black = rgb(0, 0, 0);

dumindu

#System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

##Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

dumindu

struct Electron;

fn main() {
  let x = Electron;
}

dumindu

enum Day {
    Sunday,
    Monday, 
    Tuesday, 
    Wednesday, 
    Thursday,
    Friday,
    Saturday
}

dumindu

enum FlashMessage {
  Success, //a unit variant
  Warning{ category: i32, message: String }, //a struct variant
  Error(String) //a tuple variant
}

fn main() {
  let mut form_status = FlashMessage::Success;
  print_flash_message(form_status);
  

dumindu

// generalizing functions
//-----------------------
fn takes_anything<T>(x: T) { // x has type T, T is a generic type
}

fn takes_two_of_the_same_things<T>(x: T, y: T) { // both x and y has same type
}

fn takes_two_things<T, U>(x: T, y: U) { // multiple types
}

dumindu

Green
`````
#02C386
#5fba7d

Blue
`````
#669AFB
#4099ff
#242646 (better align with #343857)

dumindu

// 01 - - - - - - - - - - - - - - - - - - - - - -
fn getIdByUsername(username: &str) -> Option<usize> {
    //if username can be found in the system, set userId
        return Some(userId);
    //else
        None
}

//💭 So on above function, instead of setting return type as usize
// set return type as Option<usize>

dumindu

// ------- code ----------
use std::io;

fn main() {
	println!("Type someting!");

	let mut input = String::new();
	match io::stdin().read_line(&mut input) {
	    Ok(n) => println!("You input {}({} bytes)", input, n),
	    Err(error) => println!("error: {}", error)

dumindu

use std::io;

fn main() {
	let i_default: u64 = 4;
	let d_default: f64 = 4.0;
	let s_default = "HackerRank ".to_string();

	let mut input = String::new();

	println!("Type second integer!");