Beginning Rust

Overview

The fizz buzz challenge is reportedly used as an interview screening device for computer programmers. The problem appears trivial yet it could turn out to be a hard nut to crack, especially for those learning a specific programming language. In this tutorial, I will show how to solve the Fizz Buzz challenge In Rust Lang

The Problem

1. If a number is a multiple of 3, print Fizz instead of the number
2. If a number is a multiple of 5, print Buzz instead of the number
3. If a number is both multiple of 3 and 5, print FizzBuzz
4. Else print the number

The Approach

As I shall show shortly, the key to solving the challenge is getting the precedence right,

• Printing FizzBuzz has the highest precedence, since it wraps around multiples of 5 and 3, thus it shall come first
• Next, printing Fizz or Buzz in place of 3 and 5 respectively has same precedence and it will be handled with conditionals (if, else if ....) thus either can come immediately after FizzBuzz
• Finally, printing the number that is neither a multiple of 3, of 5, nor of both comes last.

The Solution

The following steps assume you have some rust already installed on you computer, if not check out the installation guide

1. Crate a new project with cargo, rust's default package manager. To do this, run the following command in your terminal, This will create a new folder called rust-fizz-buzz

   cargo new rust-fizz-buzz --bin
   

2. Navigate to the rust-fizz-buzz folder and open it in your preferred text editor or IDE, you should see the following listings in rust-fizz-buzz/src/main.rs

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

3. Delete println!("Hello, world!"); from the main.rs file. Now we are set to solve the challenge.

4. As mentioned in the approach, the key to the solution is getting the precedence right, for this reason, we'll take the once with highest precedence (FizzBuzz) way down to one with the least(the number). But first, let's begin by printing 1 - 100 which is the range of number we'll use.

   fn main() {
    for number in 1..101{
        println!("{}", number);
    }
   }
   

   Note that the 1..101 is used to get the precise range (1 - 100) instead of 1..100 which will return 1 - 99. Run the following command in the rust-fizz-buzz folder to verify, first with 1..100 then 1..101.

   cargo run
   

5. Update the main.rs file with the following code.

fn main() {
    for number in 1..101 {
        //fizz buzz takes highest precedence, so it comes first
        if number % 5 == 0 && number % 3 == 0 {
            println!("fizz buzz");
        } else if number % 5 == 0 {
            println!("buzz");
        } else if number % 3 == 0 {
            println!("fizz");
        } else {
            println!("{}", number);
        }
    }
}

Run the following command, the rust-fizz-buzz folder.

cargo run

If all goes well, you should get an output similar to this