🦀 Rust – Booleans: Logic Control with true and false

Introduction – Why Learn Booleans in Rust?

Booleans are a fundamental part of logic control in Rust. Whether you’re making decisions with if statements, handling pattern matching, or looping, you’ll need to work with bool values effectively.

In this guide, you’ll learn:

• How to declare and use boolean variables
• Boolean expressions and comparison operators
• How booleans interact with if, match, and control flow
• Common use cases and logic-based patterns in Rust

Boolean Type in Rust

Rust uses the bool type with two values:

let is_rust_fun: bool = true;
let is_boring = false;

By default, bool values are immutable unless declared with mut.

Boolean Expressions with Comparisons

fn main() {
    let age = 18;
    let is_adult = age >= 18;

    println!("Is adult? {}", is_adult);
}

Logical Operators

fn main() {
    let x = true;
    let y = false;

    println!("AND: {}", x && y); // false
    println!("OR: {}", x || y);  // true
    println!("NOT x: {}", !x);   // false
}

Use Booleans in Control Flow

If-Else Example

fn main() {
    let has_access = true;

    if has_access {
        println!("Access granted.");
    } else {
        println!("Access denied.");
    }
}

Match with Booleans

fn main() {
    let is_active = false;

    match is_active {
        true => println!("Active!"),
        false => println!("Inactive!"),
    }
}

Boolean Return from Functions

fn is_even(num: i32) -> bool {
    num % 2 == 0
}

fn main() {
    println!("Is 6 even? {}", is_even(6));
}

Common Boolean Mistakes

Unlike C or Python, Rust does not auto-convert 0 to false or 1 to true.

Summary – Recap & Next Steps

Booleans in Rust power your decision-making logic. They are type-safe, explicit, and enforced by the compiler to prevent common logic errors seen in other languages.

Key Takeaways:

• Rust’s bool type only has true or false
• Use comparison (==, !=) and logical (&&, ||, !) operators
• Booleans work cleanly with if, match, and function returns
• Rust does not allow implicit boolean coercion from integers

Next: Explore Rust – Operators to understand arithmetic, logical, and bitwise operations in Rust.

FAQs

Does Rust allow using numbers in if conditions like C or Python?
No. Rust strictly requires a bool value in if conditions. You cannot use integers directly.

Can I return a boolean from a function?
Yes. Rust functions can return bool types just like any other type.

What is the type of true in Rust?
The type is bool. It’s a built-in primitive type in Rust.

Is bool mutable in Rust?
Like other variables, bool is immutable by default. Use mut if you want to change its value.

let mut flag = true;
flag = false;