Conditionals

Conditionals run different code depending on a boolean condition. In Rust, if/else works as a statement and also as an expression that produces a value.

Basic if/else

The condition must be a bool; Rust does not treat numbers as truthy.

fn main() {
    let number = 7;
    if number > 5 {
        println!("Greater than five");
    } else {
        println!("Five or less");
    }
}

else if

fn main() {
    let score = 75;
    if score >= 90 {
        println!("A");
    } else if score >= 70 {
        println!("B");
    } else {
        println!("C");
    }
}

if as an expression

Because if returns a value, you can assign its result directly. Both branches must produce the same type.

fn main() {
    let age = 20;
    let category = if age >= 18 { "adult" } else { "minor" };
    println!("{}", category);
}

This replaces the ternary operator found in other languages and keeps the code expressive and concise.