a9.operators.md

title	slug
Operators	operators

Arithmetic Operators

+ - * / %

let a = 5;
let b = a + 1; // 6
let c = a - 1; // 4
let d = a * 2; // 10
let e = a / 2; // ⭐️ 2 not 2.5
let f = a % 2; // 1

let g = 5.0 / 2.0; // 2.5

Comparison Operators

== != < > <= >=

let a = 1;
let b = 2;

let c = a == b; // false
let d = a != b; // true
let e = a < b; // true
let f = a > b; // false
let g = a <= a; // true
let h = a >= a; // true

// 🔎
let i = true > false; // true
let j = 'a' > 'A'; // true

Logical Operators

! && ||

let a = true;
let b = false;

let c = !a; // false
let d = a && b; // false
let e = a || b; // true

🔎 On integer types,! inverts the individual bits in the two’s complement representation of the value.

let a = !-2; // 1
let b = !-1; // 0
let c = !0; // -1
let d = !1; // -2

Bitwise Operators

& | ^ << >>

let a = 1;
let b = 2;

let c = a & b; // 0  (01 && 10 -> 00)
let d = a | b; // 3  (01 || 10 -> 11)
let e = a ^ b; // 3  (01 != 10 -> 11)
let f = a << b; // 4  (Add b number of 0s to the end of a -> '01'+'00' -> 100)
let g = a >> b; // 0  (Remove b number of bits from the end of a -> o̶1̶ -> 0)

Assignment and Compound Assignment Operators

The = operator is used to assign a name to a value or a function. Compound Assignment Operators are created by composing one of + - * / % & | ^ << >> operators with = operator.

let mut a = 2;

a += 5; // 2 + 5 = 7
a -= 2; // 7 - 2 = 5
a *= 5; // 5 * 5 = 25
a /= 2; // 25 / 2 = 12 not 12.5
a %= 5; // 12 % 5 = 2

a &= 2; // 10 && 10 -> 10 -> 2
a |= 5; // 010 || 101 -> 111 -> 7
a ^= 2; // 111 != 010 -> 101 -> 5
a <<= 1; // '101'+'0' -> 1010 -> 10
a >>= 2; // 101̶0̶ -> 10 -> 2

Type Casting Operator

as

let a = 15;
let b = (a as f64) / 2.0; // 7.5

Borrowing and Dereference Operators

& &mut *

🔎 The & or &mut operators are used for borrowing and * operator for dereferencing. For more information, refer Ownership, Borrowing & Lifetimes sections.

Path Separator and Member Access Operators

:: .

🔎 We discussed the usage of the :: and . operators when calling associated functions and methods under Functions.

💯 Also, the :: operator is used to access modules, constants, structs, enums, functions (excluding methods) in std modules, crates or nested/ parent modules and to access variants of enums.

💯 Also, the . operator is used to access fields of tuples and structs and to call methods in datatypes.

use std::collections::HashMap; // 💡load HashMap struct from the std::collections module

fn main() {
    // 💡 using `HashMap::from()` associated function to create a HashMap
    let best_movies = HashMap::from([
        ("01", "The Shawshank Redemption"),
        ("02", "The Godfather"),
        ("03", "The Dark Knight"),
    ]);

    println!("{:?}", best_movies);
}

println!("{}", std::primitive::u8::MAX); // 💡 access MAX constant from the std::primitive::u8

let mut a = (1, "Steve"); // 💡 a is a tuple

// 💡 access fields via dot operator
a.0 = 2;
a.1 = "Tim";
println!("{} {}", a.0, a.1); // 2 Tim

👨‍🏫 Before going to the next...

• About string concatenation,

  let (s1, s2) = ("abc", "123"); // both &str
  // All bellow codes return abc123 (in String data type)
  
  // 1. via + operator
  let s = String::from(s1) + s2; // String + &str
  
  // 2. via push_str method
  let mut s = String::from(s1);
  s.push_str(s2); // String + &str
  
  // 3. via format! macro
  let s = format!("{s1}{s2}"); // &str/String + &str/String
  
  // 4. via concat method
  let s = [s1, s2].concat(); // &str or String array