一、Vector 

fn main() {
    //let mut v= Vec::new();
     let mut v = vec![1,2,3];
    v.push(4);
    let third: &i32 = &v[2];
    println!("the third value is {}",third)
}

因为first是不可变的，所以就报错了；因为vector数据在内存中是连续的

fn main() {
    //let mut v= Vec::new();
     let mut v = vec![1,2,3];
    v.push(4);
    let third: &i32 = &v[2];
    println!("the third value is {}",third);

    // for循环遍历vector
    let mut newVector = vec![100,32,88];
    for eachData in &mut newVector {
        *eachData +=50;
        println!("{}",eachData);
    }

}

enum包装不同类型数据，再放到vector下面