我如何从Rust中的Vec获取可变元素

Question

我是Rust的新手，我正在尝试在Vec<i32>函数中获取swap()元素并更改它：

use std::ops::Index;
fn main() {
    let mut vec = Vec::new();
    for i in 0..10 {
        vec.push(i);
        print!("{} ", i);
    }
    println!(" <- Before sort");
    bubble_sort(&mut vec);
    for i in &vec {
        print!("{} ", i);
    }
    println!(" <- After sort");
}

fn bubble_sort(vec: &mut Vec<i32>) {
    for j in 0..(vec.len() - 1) {
        for i in 0..(vec.len() - j - 1) {
            if vec[i] < vec[i + 1] {
                swap(vec.index(i), vec.index(i + 1));
            }
        }
    }
}

fn swap<'l>(a: &'l mut i32, b: &'l mut i32) {
    let temp = *a;
    *a = *b;
    *b = temp;
}

我应该将元素设置为可变元素？ 如果我尝试在swap(vec.index(i), vec.index(i+1));中执行，则会显示error: cannot borrow immutable borrowed content as mutable