Rust中的Vector类型

常用类型操作，

如python中的list,turple,dictory等，

更方常编程常用数据的处理。

fn main() {
    let v = vec![, , , , ];
 
    let third: &i32 = &v[];
    println!("The third element is {}", third);
 
    match v.) {
    Some(third) => println!("The element is {}", third),
        None => println!("There is no element"),
    }
 
    match v.) {
        Some(twenty) => println!("The element is {}", twenty),
        None => println!("There is no element"),
    }
 
}