Functions, Statements, and Expressions

Updated

October 31, 2026

Functions, Statements, and Expressions

Rust is an expression-oriented language. Almost every construct evaluates to a value.

Statements vs. Expressions

Statements: Instructions that perform an action and do not return a value. Ending an expression with a semicolon ; turns it into a statement returning unit ().
Expressions: Evaluate to a resulting value. Omission of the final semicolon returns the expression value.

fn add(a: i32, b: i32) -> i32 {
    a + b // No semicolon: implicit return
}

fn compute_block(factor: i32) -> i32 {
    let result = {
        let base = 100;
        base * factor // Expression evaluated and bound to result
    };
    result
}

fn main() {
    println!("Add: {}", add(10, 20));
    println!("Compute block: {}", compute_block(3));
}