formatted-output

[giscus[bot]]

formatted-output

Learning Rust By Practice, narrowing the gap between beginner and skilled-dev with challenging examples, exercises and projects.

https://zh.practice.rs/formatted-output.html

[ADkun]

第1题

/* 填空 */
fn main() {
    println!("{0}, this is {1}. {1}, this is {0}", "Alice", "Bob");// => Alice, this is Bob. Bob, this is Alice
    assert_eq!(format!("{1}{0}", 1, 2), "21");
    assert_eq!(format!("{1}{0}{}{}", 1, 2), "2112");
    println!("Success!");
}

第2题

fn main() {
    println!("{argument}", argument = "test"); // => "test"

    /* 填空 */
    assert_eq!(format!("{name}{}", 1, name=2), "21");
    assert_eq!(format!("{a} {c} {b}",a = "a", b = 'b', c = 3 ), "a 3 b");
    
    /* 修复错误 */
    // 具名参数必须放在其它参数后面
    println!("{abc} {0}", 2, abc = "def");

    println!("Success!")
}

第3题

fn main() {
    // 下面两个都是通过 5 个空格来填充
    println!("Hello {:5}!", "x"); // =>  "Hello x    !"  
    println!("Hello {:1$}!", "x", 5); // =>  "Hello x    !"

    /* 填空 */
    assert_eq!(format!("Hello {:1$}!", "x", 5), "Hello x    !");
    assert_eq!(format!("Hello {:width$}!", "x", width = 5), "Hello x    !");

    println!("Success!")
}

第4题

fn main() {
    // 左对齐
    println!("Hello {:<5}!", "x"); // => Hello x    !
    // 右对齐
    assert_eq!(format!("Hello {:>5}!", "x"), "Hello     x!");
    // 居中对齐
    assert_eq!(format!("Hello {:^5}!", "x"), "Hello   x  !");

    // 左对齐，并使用 `&` 填充
    assert_eq!(format!("Hello {:&<5}!", "x"), "Hello x&&&&!");

    println!("Success!")
}

第5题

fn main() {
    println!("Hello {:5}!", 5); // => Hello     5!
    println!("Hello {:+}!", 5); // =>  Hello +5!
    println!("Hello {:05}!", 5); // => Hello 00005!
    println!("Hello {:05}!", -5); // => Hello -0005!

    /* 填空 */
    assert!(format!("{number:0>width$}", number=1, width=6) == "000001");
    
    println!("Success!")
}

第6题

/* 填空 */
fn main() {
    let v = 3.1415926;

    println!("{:.1$}", v, 4); // same as {:.4} => 3.1416 

    assert_eq!(format!("{:.2}", v), "3.14");
    assert_eq!(format!("{:+.2}", v), "+3.14");
    assert_eq!(format!("{:.0}", v), "3");

    println!("Success!")
}

第7题

fn main() {
    let s = "Hello, world!";

    println!("{0:.5}", s); // => Hello

    assert_eq!(format!("Hello {1:.0$}!", 3, "abcdefg"), "Hello abc!");

    println!("Success!")
}

第8题

fn main() {
    assert_eq!(format!("{:#b}", 27), "0b11011");
    assert_eq!(format!("{:#o}", 27), "0o33");
    assert_eq!(format!("{:#x}", 27), "0x1b");
    assert_eq!(format!("{:#X}", 27), "0x1B");

    println!("{:x}!", 27); // 没有前缀的十六进制 => 1b

    println!("{:#010b}", 27); // 使用 0 来填充二进制，宽度为 10 => 0b00011011

    println!("Success!")
}

第9题

fn get_person() -> String {
    String::from("sunface")
}

fn get_format() -> (usize, usize) {
    (4, 1)
}


fn main() {
    let person = get_person();
    println!("Hello, {person}!");

    let (width, precision) = get_format();
    let scores = [("sunface", 99.12), ("jack", 60.34)];
    /* 让下面的代码输出:
    sunface:   99.1
    jack:   60.3
    */
    for (name, score) in scores {
        println!("{name}: {score:.1}");
    }
}