While loop in Rust - Mini Project: Build & Apply

Counting Down with a While Loop in Rust

📖 Scenario: Imagine you have a countdown timer for a game or event. You want to count down from a starting number to zero, showing each number as it goes down.

🎯 Goal: You will create a Rust program that uses a while loop to count down from a number to zero and print each number.

📋 What You'll Learn

Create a variable called count with the starting number 5

Create a variable called step with the value 1

Use a while loop that runs while count is greater than or equal to 0

Inside the loop, print the current value of count

Inside the loop, decrease count by step

Print the final message "Countdown finished!" after the loop ends

💡 Why This Matters

🌍 Real World

Countdown timers are used in games, cooking timers, and event reminders to show time left.

💼 Career

Understanding loops and conditions is essential for programming tasks like automation, game development, and system monitoring.

1

Create the countdown starting number

Create a variable called count and set it to the number 5.

Rust

# Create a variable called count and set it to 5
# Your code here

Need a hint?

Use let mut count = 5; to create a variable that can change.

2

Add the step variable

Add a variable called step and set it to 1 inside the main function, below count.

Rust

fn main() {
    let mut count = 5;
    // Create a variable called step and set it to 1
    // Your code here
}

Need a hint?

Use let step = 1; to create a fixed step size.

3

Write the while loop to count down

Write a while loop that runs while count is greater than or equal to 0. Inside the loop, print the value of count and then subtract step from count.

Rust

fn main() {
    let mut count = 5;
    let step = 1;

    // Write a while loop that runs while count >= 0
    // Inside the loop, print count and subtract step from count
    // Your code here
}

Need a hint?

Use while count >= 0 { ... } and inside print with println!("{}", count); then subtract with count -= step;.

4

Print the final message after the loop

After the while loop, write a println! statement to print "Countdown finished!".

Rust

fn main() {
    let mut count = 5;
    let step = 1;

    while count >= 0 {
        println!("{}", count);
        count -= step;
    }

    // Print "Countdown finished!" here
    // Your code here
}

Need a hint?

Use println!("Countdown finished!"); after the loop.