Reference Primitives

References (&T และ &mut T)

Creating References

fn main() {
    let x = 42;

    // Immutable reference
    let ref_x: &i32 = &x;
    println!("ref_x: {}", ref_x);
    println!("*ref_x: {}", *ref_x);  // Deref

    // Multiple immutable references OK
    let ref_a = &x;
    let ref_b = &x;
    println!("Both: {} {}", ref_a, ref_b);

    // Mutable reference
    let mut y = 100;
    {
        let ref_mut: &mut i32 = &mut y;
        *ref_mut = 200;
        println!("Through ref: {}", ref_mut);
    }  // ref_mut ends

    println!("After: {}", y);

    // Can't have mutable and immutable at same time
    // let r1 = &y;
    // let r2 = &mut y;  // Error!

    // Auto-deref in method calls
    let s = String::from("hello");
    let len = (&s).len();  // Auto-derefs to &str
    println!("Length: {}", len);
}