use ::anyhow::Result;

fn main() -> Result<()> {
    let mut arr = [1, 2, 3];
    println!("{:?}", arr);
    let p1 = arr.as_mut_ptr();
    let p1_size = p1 as usize;
    let p2 = (p1_size + 4) as *mut i32;
    println!("{:?}", p2);
    unsafe {
        *p2 += 40;
    }
    println!("{:?}", arr);
    Ok(())
}