The Ultimate Guide to Rust Programming/

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Blocks and Statements

Blocks and Statements

We'll cover the following...

Let’s revisit our Hello World program and build up from there:

Rust 1.40.0
fn main() {
    println!("Hello, world!");
}

The curly braces part is called a block. And as you’ve already seen in other examples, you’re not limited to just one println! macro call. You can have as many as you like:

Rust 1.40.0
fn main() {
    println!("Hello, world!");
    println!("Still alive!");
    println!("I'm tired, good night!");
}

Exercise Comment out all three of the println! calls and see what happens.

Let’s look at another program:

Rust 1.40.0
fn main() {
    let x: i32 = 4 + 5;
    println!("4 + 5 == {}", x);
}

Just for kicks, I’m going to wrap the right-hand side of let x = in curly braces:

Rust 1.40.0
fn main() {
    let x: i32 = { 4 + 5 };
    println!("4 + 5 == {}", x);
}

What we’ve done here is create a new block, and put the expression 4 + 5 inside of it. Blocks themselves are expressions, and ...