rustµÄÄÚ´æ¹ÜÀí

use std::panic; 
use std::cell::Cell; 

#[derive(Debug)]
struct A;

impl Drop for A {
    fn drop(&mut self) {
        println!("a went away");
    }
}

fn change_str(s :&mut String) {
    s.push_str(" world")
}

fn box_ref<T> (b: T) -> Box<T> {
    let a = b;
    Box::new(a)
}

#[derive(Debug)]
struct B {
    item: Box<u32>
}


#[derive(Clone, Debug)]
struct C {
    i: u32
}


#[derive(Debug)]
struct Number<'a> { 
    num: &'a u8 
}

impl<'a> Number<'a> { 
    fn get_num(&self) -> &'a u8 { 
        self.num 
    }  
    fn set_num(&mut self, new_number: &'a u8) { 
        self.num = new_number 
    }
}


fn main() {
    let a1 = A;
    let a2  = &a1;
    println!("{:?},{:?}", a1,a2);

    let mut hi =  String::from("hello");
    change_str(&mut hi);
    println!("{}", hi);


    let a3 = Box::new(A);
    let a4 = a3;
    println!("{:?}",a4);
    let a5 = box_ref(a4);
    println!("{:?}",a5);


    /*
    panic::catch_unwind(||{
        panic!("test")
    }).ok();
    println!("over panic");
    */

    let b1 = Cell::new(B { item: Box::new(1) });
    let b2 = &b1;
    let b3 = &b1;
    b2.set(B { item: Box::new(2)}); 
    b3.set(B { item: Box::new(3)});

    let c1 = C{i:1};
    let mut c2 = c1.clone();
    c2.i = 222;

    println!("c1: {:?}, c2: {:?}", c1, c2);

    let na = 10;
    let mut num = Number { num: &na };
    num.set_num(&23);
    println!("{:?}", num.get_num());

}