【rCore OS 开源操作系统】Rust 练习题题解: Structs

【rCore OS 开源操作系统】Rust 练习题题解: Structs

摘要

rCore OS 开源操作系统训练营学习中的代码练习部分。

在此记录下自己学习过程中的产物,以便于日后更有"收获感"。

后续还会继续完成其他章节的练习题题解。

正文

structs1

题目
rust 复制代码
// structs1.rs
//
// Address all the TODOs to make the tests pass!
//
// Execute `rustlings hint structs1` or use the `hint` watch subcommand for a
// hint.

// I AM NOT DONE

struct ColorClassicStruct {
    // TODO: Something goes here
}

struct ColorTupleStruct(
    /* TODO: Something goes here */
);

#[derive(Debug)]
struct UnitLikeStruct;

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn classic_c_structs() {
        // TODO: Instantiate a classic c struct!
        // let green =

        assert_eq!(green.red, 0);
        assert_eq!(green.green, 255);
        assert_eq!(green.blue, 0);
    }

    #[test]
    fn tuple_structs() {
        // TODO: Instantiate a tuple struct!
        // let green =

        assert_eq!(green.0, 0);
        assert_eq!(green.1, 255);
        assert_eq!(green.2, 0);
    }

    #[test]
    fn unit_structs() {
        // TODO: Instantiate a unit-like struct!
        // let unit_like_struct =
        let message = format!("{:?}s are fun!", unit_like_struct);

        assert_eq!(message, "UnitLikeStructs are fun!");
    }
}
题解

参考定义和举例说明结构体 - Rust 程序设计语言 中文版》第五章

structs 的基本如下:

rust 复制代码
// 定义
struct User {
    age: i32,
    active: bool,
    username: String,
    email: String,
    sign_in_count: u64,
}
// 实现方法
impl User{
    fn info(&self) -> i32 {
        &self.age + 1 // 不加分号,就是 tail exp, 自带 return
    }
}
// 实例化
let rect1 = Rectangle {
    width: 30,
    height: 50,
};

 rect1.area()
 
 // 元组结构体定义
 struct User2(i32, i32, i32);
 let user = User2(1, 1, 1);
 // 类单元结构体定义
 struct User3;
 let user3 = User3;

所以答案也就是呼之欲出了:

rust 复制代码
// structs1.rs
//
// Address all the TODOs to make the tests pass!
//
// Execute `rustlings hint structs1` or use the `hint` watch subcommand for a
// hint.

struct ColorClassicStruct {
    // TODO: Something goes here
    red: i32,
    green: i32,
    blue: i32,
}

struct ColorTupleStruct(/* TODO: Something goes here */ i32, i32, i32);

#[derive(Debug)]
struct UnitLikeStruct;

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn classic_c_structs() {
        // TODO: Instantiate a classic c struct!
        let green = ColorClassicStruct {
            red: 0,
            green: 255,
            blue: 0,
        };

        assert_eq!(green.red, 0);
        assert_eq!(green.green, 255);
        assert_eq!(green.blue, 0);
    }

    #[test]
    fn tuple_structs() {
        // TODO: Instantiate a tuple struct!
        let green = ColorTupleStruct(0, 255, 0);

        assert_eq!(green.0, 0);
        assert_eq!(green.1, 255);
        assert_eq!(green.2, 0);
    }

    #[test]
    fn unit_structs() {
        // TODO: Instantiate a unit-like struct!
        let unit_like_struct = UnitLikeStruct;
        let message = format!("{:?}s are fun!", unit_like_struct);

        assert_eq!(message, "UnitLikeStructs are fun!");
    }
}

Structs2

题目
rust 复制代码
// structs2.rs
//
// Address all the TODOs to make the tests pass!
//
// Execute `rustlings hint structs2` or use the `hint` watch subcommand for a
// hint.

// I AM NOT DONE

#[derive(Debug)]
struct Order {
    name: String,
    year: u32,
    made_by_phone: bool,
    made_by_mobile: bool,
    made_by_email: bool,
    item_number: u32,
    count: u32,
}

fn create_order_template() -> Order {
    Order {
        name: String::from("Bob"),
        year: 2019,
        made_by_phone: false,
        made_by_mobile: false,
        made_by_email: true,
        item_number: 123,
        count: 0,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn your_order() {
        let order_template = create_order_template();
        // TODO: Create your own order using the update syntax and template above!
        // let your_order =
        assert_eq!(your_order.name, "Hacker in Rust");
        assert_eq!(your_order.year, order_template.year);
        assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
        assert_eq!(your_order.made_by_mobile, order_template.made_by_mobile);
        assert_eq!(your_order.made_by_email, order_template.made_by_email);
        assert_eq!(your_order.item_number, order_template.item_number);
        assert_eq!(your_order.count, 1);
    }
}
解析

第二章节主要是考察结构体方法的实现。

参考:https://doc.rust-lang.org/stable/book/ch05-01-defining-structs.html#creating-instances-from-other-instances-with-struct-update-syntax

这里提到的update语法,是类似 JS 中的对象展开+字段覆盖的操作。

但是这里的覆盖是有固定优先级的,和字段书写顺序无关

rust 复制代码
// structs2.rs
//
// Address all the TODOs to make the tests pass!
//
// Execute `rustlings hint structs2` or use the `hint` watch subcommand for a
// hint.

#[derive(Debug)]
struct Order {
    name: String,
    year: u32,
    made_by_phone: bool,
    made_by_mobile: bool,
    made_by_email: bool,
    item_number: u32,
    count: u32,
}

fn create_order_template() -> Order {
    Order {
        name: String::from("Bob"),
        year: 2019,
        made_by_phone: false,
        made_by_mobile: false,
        made_by_email: true,
        item_number: 123,
        count: 0,
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn your_order() {
        let order_template = create_order_template();
        // TODO: Create your own order using the update syntax and template above!
        let your_order = Order {
            name: String::from("Hacker in Rust"),
            count: 1,
            ..order_template
        };

        assert_eq!(your_order.name, "Hacker in Rust");
        assert_eq!(your_order.year, order_template.year);
        assert_eq!(your_order.made_by_phone, order_template.made_by_phone);
        assert_eq!(your_order.made_by_mobile, order_template.made_by_mobile);
        assert_eq!(your_order.made_by_email, order_template.made_by_email);
        assert_eq!(your_order.item_number, order_template.item_number);
        assert_eq!(your_order.count, 1);
    }
}

Structs3

题目
rust 复制代码
// structs3.rs
//
// Structs contain data, but can also have logic. In this exercise we have
// defined the Package struct and we want to test some logic attached to it.
// Make the code compile and the tests pass!
//
// Execute `rustlings hint structs3` or use the `hint` watch subcommand for a
// hint.

// I AM NOT DONE

#[derive(Debug)]
struct Package {
    sender_country: String,
    recipient_country: String,
    weight_in_grams: i32,
}

impl Package {
    fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
        if weight_in_grams <= 0 {
            panic!("Can not ship a weightless package.")
        } else {
            Package {
                sender_country,
                recipient_country,
                weight_in_grams,
            }
        }
    }

    fn is_international(&self) -> ??? {
        // Something goes here...
    }

    fn get_fees(&self, cents_per_gram: i32) -> ??? {
        // Something goes here...
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[should_panic]
    fn fail_creating_weightless_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Austria");

        Package::new(sender_country, recipient_country, -2210);
    }

    #[test]
    fn create_international_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Russia");

        let package = Package::new(sender_country, recipient_country, 1200);

        assert!(package.is_international());
    }

    #[test]
    fn create_local_package() {
        let sender_country = String::from("Canada");
        let recipient_country = sender_country.clone();

        let package = Package::new(sender_country, recipient_country, 1200);

        assert!(!package.is_international());
    }

    #[test]
    fn calculate_transport_fees() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Spain");

        let cents_per_gram = 3;

        let package = Package::new(sender_country, recipient_country, 1500);

        assert_eq!(package.get_fees(cents_per_gram), 4500);
        assert_eq!(package.get_fees(cents_per_gram * 2), 9000);
    }
}
解析

根据意思,补全结构体的方法实现,对比是否为同一个地区,判断是否相同,以及计算费用,比较简单。

rust 复制代码
// structs3.rs
//
// Structs contain data, but can also have logic. In this exercise we have
// defined the Package struct and we want to test some logic attached to it.
// Make the code compile and the tests pass!
//
// Execute `rustlings hint structs3` or use the `hint` watch subcommand for a
// hint.

#[derive(Debug)]
struct Package {
    sender_country: String,
    recipient_country: String,
    weight_in_grams: i32,
}

impl Package {
    fn new(sender_country: String, recipient_country: String, weight_in_grams: i32) -> Package {
        if weight_in_grams <= 0 {
            panic!("Can not ship a weightless package.")
        } else {
            Package {
                sender_country,
                recipient_country,
                weight_in_grams,
            }
        }
    }

    fn is_international(&self) -> bool {
        // Something goes here...
        &self.sender_country != &self.recipient_country
    }

    fn get_fees(&self, cents_per_gram: i32) -> i32 {
        // Something goes here...
        &self.weight_in_grams * cents_per_gram
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[should_panic]
    fn fail_creating_weightless_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Austria");

        Package::new(sender_country, recipient_country, -2210);
    }

    #[test]
    fn create_international_package() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Russia");

        let package = Package::new(sender_country, recipient_country, 1200);

        assert!(package.is_international());
    }

    #[test]
    fn create_local_package() {
        let sender_country = String::from("Canada");
        let recipient_country = sender_country.clone();

        let package = Package::new(sender_country, recipient_country, 1200);

        assert!(!package.is_international());
    }

    #[test]
    fn calculate_transport_fees() {
        let sender_country = String::from("Spain");
        let recipient_country = String::from("Spain");

        let cents_per_gram = 3;

        let package = Package::new(sender_country, recipient_country, 1500);

        assert_eq!(package.get_fees(cents_per_gram), 4500);
        assert_eq!(package.get_fees(cents_per_gram * 2), 9000);
    }
}
相关推荐
NocoBase6 小时前
6 个替代 Jira 的开源项目管理工具推荐
低代码·开源·github
专注VB编程开发20年7 小时前
CSS 的命名方式像是 PowerShell 的动词-名词结构,缺乏面向对象的层级关系
开发语言·后端·rust
算家计算8 小时前
一站式高质量数字人动画框架——EchoMimic-V3本地部署教程: 13 亿参数实现统一多模态、多任务人体动画生成
人工智能·开源
ai产品老杨8 小时前
驱动物流创新与协同,助力物流行业可持续发展的智慧物流开源了
人工智能·开源·音视频·能源
伍哥的传说8 小时前
Tailwind CSS v4 终极指南:体验 Rust 驱动的闪电般性能与现代化 CSS 工作流
前端·css·rust·tailwindcss·tailwind css v4·lightning css·utility-first
专注VB编程开发20年11 小时前
rust语言-对象多级访问
服务器·前端·rust
ajassi200011 小时前
开源 C++ QT Widget 开发(十三)IPC通讯--本地套接字 (Local Socket)
linux·c++·qt·开源
编码浪子14 小时前
趣味学RUST基础篇(构建一个命令行程序2重构)
开发语言·重构·rust
susnm15 小时前
组件生命周期
rust·全栈
bruce5411016 小时前
Axum 最佳实践:如何构建优雅的 Rust 错误处理系统?(三)
rust