【rCore OS 开源操作系统】Rust 练习题题解: Structs

news/2024/10/4 0:01:09 标签: rust, 操作系统, OS, 内存安全, 开源

OS_Rust__Structs_0">【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">// 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">// 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">// 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">// 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">// 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">// 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">// 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);
    }
}

http://www.niftyadmin.cn/n/5689148.html

相关文章

【STM32开发笔记】移植AI框架TensorFlow到STM32单片机【下篇】

【STM32开发笔记】移植AI框架TensorFlow到STM32单片机【下篇】

【STM32开发笔记】移植AI框架TensorFlow到STM32单片机【下篇】 一、上篇回顾二、项目准备2.1 准备模板项目2.2 支持计时功能2.3 配置UART4引脚2.4 支持printf重定向到UART42.5 支持printf输出浮点数2.6 支持printf不带\r的换行2.7 支持ccache编译缓存 三、TFLM集成3.1 添加tfli…
阅读更多...
Prometheus之Pushgateway使用

Prometheus之Pushgateway使用

Pushgateway属于整个架构图的这一部分 The Pushgateway is an intermediary service which allows you to push metrics from jobs which cannot be scraped. The Prometheus Pushgateway exists to allow ephemeral and batch jobs to expose their metrics to Prometheus. S…
阅读更多...
Solidity 存储和内存管理：深入理解与高效优化

Solidity 存储和内存管理：深入理解与高效优化

在 Solidity 中&#xff0c;存储和内存管理是编写高效智能合约的关键组成部分。合约执行的每一步操作都可能涉及到数据的存储和读取&#xff0c;而这些操作对 gas 的消耗有很大影响。因此&#xff0c;理解 Solidity 的存储模型以及如何优化数据的管理对于合约的安全性、性能和成…
阅读更多...
汇编语言知识（王爽第四版）

汇编语言知识（王爽第四版）

汇编语言&#xff0c;当然&#xff0c;我们学习是在c语言的基础上&#xff0c;那么&#xff0c;我们就先复习一下c语言的知识 C语言的基础&#xff0c;进制转换必不可少 数组&#xff0c;函数…… 接下来&#xff0c;我们学习了数据结构&#xff1a;顺序表&#xff0c;链表&…
阅读更多...
Arduino UNO R3自学笔记18 之 Arduino的外部中断、定时中断介绍及应用

Arduino UNO R3自学笔记18 之 Arduino的外部中断、定时中断介绍及应用

注意&#xff1a;学习和写作过程中&#xff0c;部分资料搜集于互联网&#xff0c;如有侵权请联系删除。 前言&#xff1a;上篇写了为啥要用中断&#xff0c;这篇具体展开写Arduino中断相关的知识。 温习&#xff1a;单片机在执行程序时&#xff0c;发生一些其它紧急的事情&…
阅读更多...
[Leetcode LCR188.][Medium]-买卖芯片的最佳时机-dp/状态压缩

[Leetcode LCR188.][Medium]-买卖芯片的最佳时机-dp/状态压缩

目录 一、题目描述 二、整体思路 三、代码 一、题目描述 原题地址 二、整体思路 可以设一个长度为price.length的dp数组,dp[i]表示到第i天时的最大利润。因为买入操作只能在卖出操作之前完成,因此需要记录下遍历prices数组到第i天时历史最低价格minp,每次遍历都要更新历史…
阅读更多...
vmvare虚拟机centos 忘记超级管理员密码怎么办？

vmvare虚拟机centos 忘记超级管理员密码怎么办？

vmvare虚拟机centos 忘记超级管理员密码怎么办？如何重置密码呢？ 一、前置操作 重启vmvare虚拟机的过程中，长按住Shift键 选择第一个的时候，按下按键 e 进入编辑状态。 然后就会进入到类似这个界面中。 在下方界面 添加 init=/bin/sh,然后按下Ctrl+x进行保存退出。 init=/bi…
阅读更多...
vue项目-仿知乎页面的路由跳转

vue项目-仿知乎页面的路由跳转

这篇文章记录一下该项目的路由跳转&#xff0c;首先是登录页 登录页路由跳转到首页也就是index文件夹中 然后展示contentleft组件和contentright组件&#xff0c;他们在页面上的显示是这样的 然后每一个功能部分也会有另一个url&#xff0c;去跳转更详细的界面 有时间继续…
阅读更多...
最新文章

Copyright @ 2022~2023