深入理解 Rust 中的模式匹配语法(最新推荐)

fn main() {
    let x = 1;
    match x {
        1 => println!("匹配到字面量 1"),
        _ => println!("其他值"),
    }
}

fn main() {
    let x = Some(5);
    let y = 10;
    match x {
        None => println!("x 是 None"),
        Some(y) => println!("匹配到 Some，其中内部 y 为: {}", y),
    }
    println!("外部的 y: {}", y);
}

fn main() {
    let x = 2;
    match x {
        1 | 2 => println!("匹配到 1 或 2"),
        _ => println!("其他值"),
    }
}

fn main() {
    let x = 3;
    match x {
        1..=5 => println!("x 在 1 到 5 的范围内"),
        _ => println!("x 超出范围"),
    }
}

struct Point {
    x: i32,
    y: i32,
}
fn main() {
    let p = Point { x: 10, y: 20 };
    // 显式命名
    let Point { x: a, y: b } = p;
    println!("a: {}, b: {}", a, b);
    // 结构体字段的简写（变量名与字段名相同）
    let Point { x, y } = p;
    println!("x: {}, y: {}", x, y);
}

enum Message {
    Quit,
    Move { x: i32, y: i32 },
    Write(String),
    ChangeColor(i32, i32, i32),
}
fn main() {
    let msg = Message::ChangeColor(255, 160, 0);
    match msg {
        Message::Quit => println!("Quit!"),
        Message::Move { x, y } => println!("Move to ({}, {})", x, y),
        Message::Write(text) => println!("Text message: {}", text),
        Message::ChangeColor(r, g, b) => println!("Change color to red: {}, green: {}, blue: {}", r, g, b),
    }
}

enum Color {
    Rgb(i32, i32, i32),
    Hsv(i32, i32, i32),
}
enum Message {
    ChangeColor(Color),
    // 其他变体...
}
fn main() {
    let msg = Message::ChangeColor(Color::Rgb(0, 160, 255));
    match msg {
        Message::ChangeColor(Color::Rgb(r, g, b)) =>
            println!("Change the color to red: {}, green: {}, blue: {}", r, g, b),
        Message::ChangeColor(Color::Hsv(h, s, v)) =>
            println!("Change the color using HSV: {}, {}, {}", h, s, v),
        _ => (),
    }
}

fn main() {
    let x = 3;
    match x {
        _ => println!("忽略具体值"),
    }
}

fn main() {
    let setting_value = Some(5);
    let new_setting_value = Some(5);
    match (setting_value, new_setting_value) {
        (Some(_), Some(_)) => println!("不能覆盖已有的自定义值"),
        _ => println!("允许更新设置"),
    }
}

struct Point3D {
    x: i32,
    y: i32,
    z: i32,
}
fn main() {
    let point = Point3D { x: 10, y: 20, z: 30 };
    match point {
        Point3D { x, .. } => println!("只关心 x 的值: {}", x),
    }
}

fn main() {
    let num = Some(4);
    match num {
        Some(x) if x % 2 == 0 => println!("数字 {} 是偶数", x),
        Some(_) => println!("匹配到 Some，但不满足守卫条件"),
        None => println!("匹配到 None"),
    }
}

fn main() {
    let id = 5;
    match id {
        id_variable @ 3..=7 => println!("找到了范围内的 id: {}", id_variable),
        _ => println!("id 不在 3 到 7 的范围内"),
    }
}