Modulo Operator

Part of the Fundamentals section of Coddy's Rust journey — lesson 16 of 75.

The modulo operator % gives the remainder of a division. In Rust, it's used with a simple syntax:

let result = dividend % divisor;

dividend: The number being divided.
divisor: The number that divides the dividend.
result: The remainder of the division.

For example:

let result = 10 % 3;

Here, 10 is divided by 3. 3 goes into 10 three times, with a remainder of 1. So, result will be 1.

Usually modulo is used for checking if a number is even or odd:

If a number is even, dividing it by 2 will leave a remainder of 0.
If a number is odd, dividing it by 2 will leave a remainder of 1.

When using modulo with floating-point numbers (f64), it works similarly to integers but keeps the decimal precision. For example:

let result: f64 = 5.2 % 2.0;
// result is 1.2

Here's how it works: 2.0 goes into 5.2 two times (4.0), and the remainder is 1.2 (5.2 - 4.0 = 1.2).

Another example:

let result: f64 = 7.8 % 3.5;
// result is 0.8

Challenge

Beginner

Write a code that initializes three variables, a (i32), b (f64) and c (i32) with the values 9, 2.6, and 11 (respectively).

After that, initialize the following variables:

d (i32) that will hold the result of a modulo 2
e (i32) that will hold the result of a modulo 3
f (f64) that will hold the result of b modulo 1.5
g (f64) that will hold the result of b modulo 3.9
h (i32) that will hold the result of c modulo 10

Check out the result and see how different dividends and divisors affect the result.

Cheat sheet

The modulo operator % gives the remainder of a division:

let result = dividend % divisor;

Example with integers:

let result = 10 % 3; // result is 1

Common use case - checking if a number is even or odd:

Even numbers: number % 2 == 0
Odd numbers: number % 2 == 1

Modulo with floating-point numbers:

let result: f64 = 5.2 % 2.0; // result is 1.2
let result: f64 = 7.8 % 3.5; // result is 0.8

Try it yourself

fn main() {
    // Type your code below
    
    
    // Don't change the line below
    println!("a = {}", a);
    println!("b = {}", b);
    println!("c = {}", c);
    println!("d = {}", d);
    println!("e = {}", e);
    println!("f = {}", f);
    println!("g = {}", g);
    println!("h = {}", h);
}