1. //rust 中的数据类型主要分为scalar and compound 标量与复合类型
    2. //单一值的为 scalar, 多值的为compound
    3. fn main(){
    4.     //数据类型转换, 接收变量必须显示指定数据类型: 变量名后面 ：数字类型
    5.     let guess: u32 = "42".parse().expect("Not a number!");
    6.     println!("The value of guess is {}", guess);
    8.     // Numeric Operations
    9.     let sum = 5 + 10;
    10.     let difference = 95.5 - 4.3;
    11.     let product = 4 * 30;
    12.     let quotient = 56.7 / 32.2;
    13.     let remainder = 43 % 5; // 取模运算
    15.     println!("The value of sum is {}", sum);
    16.     println!("The value of difference is {}", difference);
    17.     println!("The value of product is {}", product);
    18.     println!("The value of quotient is {}", quotient);
    19.     println!("The value of remainder is {}", remainder);
    21.     //character
    22.     let c = 'z';
    23.     let z = 'Z';
    24.     let heart_eyed_cat = '🐷';
    25.     println!("The value of c is {}", c);
    26.     println!("The value of z is {}", z);
    27.     println!("The value of heart_eyed_cat is {}", heart_eyed_cat);
    29.     //compound type
    30.     //tuple,fixed length can be different data type
    31.     let tup = (500,6.4,1);
    32.     let (e,f,g) = tup; //解构tuple里的值至单个变量
    33.     println!("The value of f is: {}", f);
    34.     println!("The value of e is: {}", tup.0); //用 点号 . 加索引(从0开始)访问tuple中的值
    35.     println!("The value of g is: {}", tup.2);
    36.     //Array,fixed length must be same data type
    37.     let months = ["January", "February", "March", "April",
    38.     "May", "June", "July", "August", "September", "October", "November", "December"];
    39.     println!("The value of months is {:?}", months);
    40.     let aaa: [i32; 5] = [1,2,3,4,5];//显示声明数组中元素的数据类型及数组长度并用分号分开
    41.     println!("The value of aaa is {:?}", aaa);
    42.     let bbb = [3;5];//指定数组中每个元素的值为3,并设定数组的长度为5
    43.     println!("The value of bbb is {:?}", bbb);
    44.     println!("The first value of aaa is {}", aaa[0]);//访问数组
    45.     println!("The second value of bbb is {}", bbb[1]);
    46.     //rust中越界访问数组时，在runtime会出现错误
    47. }