你如何在 Rust 中访问枚举值? [英] How do you access enum values in Rust?

问题描述

struct Point {
    x: f64,
    y: f64,
}

enum Shape {
    Circle(Point, f64),
    Rectangle(Point, Point),
}

let my_shape = Shape::Circle(Point { x: 0.0, y: 0.0 }, 10.0);

我想打印出circle的第二个属性，这里是10.0.我尝试了 my_shape.last 和 my_shape.second，但都没有奏效.

I want to print out circle's second property, which is 10.0 here. I tried my_shape.last and my_shape.second, but neither worked.

在这种情况下，我应该怎么做才能打印出 10.0?

What should I do in order to print out 10.0 in this case?

推荐答案

您可以使用模式匹配:

struct Point {
    x: f64,
    y: f64,
}

enum Shape {
    Circle(Point, f64),
    Rectangle(Point, Point),
}

fn main() {
    let my_shape = Shape::Circle(Point { x: 0.0, y: 0.0 }, 10.0);

    match my_shape {
        Shape::Circle(_, value) => println!("value: {}", value),
        _ => println!("Something else"),
    }
}

示例输出:

value: 10

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