VisualByteOrg

3 Statements and Expressions in Rust

fn main() {
    let x = 1u32;

    // expression ;
    x;
    x + 1;
    15;

    let x = 5;
    //block expression ;
    {
        5 ;
    }
    let y = {
        let x = x * x;
        2 * x
    };

    let z = {
        // The semicolon suppresses this expression and `()` is assigned to `z`
        2 * x;
    };

    println!("x is {:?}", x);
    println!("y is {:?}", y);
    println!("z is {:?}", z);
}

The same variable name can be defined multiple times

The inner scope defines a new variable x that shadows the outer x.

As a result, the value of x defined within the inner scope does not affect the value of the x in the outer scope

The result of the block expression is 2 * x, which evaluates to 50

The result of the block expression is ‘()‘

---

fn main() {
    let y = 6;

    let y = {
        let x = 3;
        x + 1
    };

    println!("The value of y is: {y}");
}

Statements are instructions that perform some action and do not return a value.

Expressions evaluate to a resultant value.

Rust is an expression-based language, which is an important distinction to understand (as opposed to other languages).

This line is a statement. The let y = 6 statement does not return a value

The 6 in the statement let y = 6; is an expression that evaluates to the value 6.

The code block {

    let x = 3;

    x + 1

} is a block expression.

---