Rust Pass by Value and Reference

core.rs

// Pass by refernce
fn double1(x: &mut [i32; 10]) {
    for i in 0..10 {
        x[i] += 2;
    }
}

// Pass by value
fn double2(x: [i32; 10]) -> [i32; 10] {
    let mut y: [i32; 10] = x;
    for i in 0..10 {
        y[i] += 2;
    }
    
    y
}

// Pass by value
fn double3(mut x: [i32; 10]) -> [i32; 10] {
    for i in 0..10 {
        x[i] += 2;
    }
    
    x
}

fn main() {
    let mut ar: [i32; 10] = [3;10];
    double1(&mut ar);
    println!("{:?}", ar);
    
    println!("{:?}", double2(ar));
    println!("{:?}", double3(ar));
}

Standard Error
   Compiling playground v0.0.1 (/playground)
    Finished dev [unoptimized + debuginfo] target(s) in 1.57s
     Running `target/debug/playground`

Standard Output
[5, 5, 5, 5, 5, 5, 5, 5, 5, 5]
[7, 7, 7, 7, 7, 7, 7, 7, 7, 7]
[7, 7, 7, 7, 7, 7, 7, 7, 7, 7]