Immutable variables in Rust - Mini Project: Build & Apply

Immutable variables

📖 Scenario: Imagine you are writing a program to store the number of days in a week. This number should never change because it is a fixed fact.

🎯 Goal: You will create an immutable variable to hold the number of days in a week, then try to use it in a simple calculation.

📋 What You'll Learn

Create an immutable variable named days_in_week with the value 7.

Create another variable named weeks with the value 3.

Calculate the total number of days in weeks weeks using days_in_week.

Print the total number of days.

💡 Why This Matters

🌍 Real World

Immutable variables are used to store fixed values that should not change, like constants or configuration values.

💼 Career

Understanding immutability is important for writing safe and predictable Rust programs, which is valuable in systems programming and software development.

1

Create an immutable variable

Create an immutable variable called days_in_week and set it to 7.

Rust

// Create an immutable variable called days_in_week and set it to 7
// Your code here

Need a hint?

Use let without mut to make the variable immutable.

2

Add a variable for weeks

Add a variable called weeks and set it to 3 inside the main function, below days_in_week.

Rust

fn main() {
    let days_in_week = 7;
    // Add a variable called weeks and set it to 3
    // Your code here
}

Need a hint?

Use let weeks = 3; to create the variable.

3

Calculate total days

Create a variable called total_days that multiplies days_in_week by weeks inside the main function.

Rust

fn main() {
    let days_in_week = 7;
    let weeks = 3;
    // Calculate total_days by multiplying days_in_week and weeks
    // Your code here
}

Need a hint?

Use let total_days = days_in_week * weeks; to calculate the total.

4

Print the total days

Print the value of total_days using println! inside the main function.

Rust

fn main() {
    let days_in_week = 7;
    let weeks = 3;
    let total_days = days_in_week * weeks;
    // Print total_days
    // Your code here
}

Need a hint?

Use println!("Total days: {}", total_days); to print the result.