有了这code on the rust playground个:
fn main() {
let a = &[1, 2, 3];
let mut o = a.to_owned();
let mut c = a.clone();
let mut d = *a;
o[0] = 7;
c[0] = 8;
d[0] = 9;
println!("o: {:?}", o);
println!("c: {:?}", c);
println!("d: {:?}", d);
println!("a: {:?}", a);
}
我明白了:
o: [7, 2, 3]
c: [8, 2, 3]
d: [9, 2, 3]
a: [1, 2, 3]
这三种方法都克隆了a的内容.
有什么不同吗？
For a reference to an instance of Copy there is no difference.
That is because for Copy types:
*ref_to_val返回val的按位副本(并且不会使旧值无效).Clone个实施.对于Copy类型，将使用*实现.clone().ToOwned加厚.对于Clone类型，将使用.clone()实现.to_owned().So it all boils down to bitwise copy.
This is your case.
If you want to understand how traits Deref, Clone, ToOwned work for !Copy types, you have to understand their purpose and read type-specific docs.
I believe String and str types are very representative !Copy types that will help you understand the magic. Eg. str is ToOwned, but not Deref or Clone. Your example won't work for these types.