网站建设的主要特征互联网广告价格

31.结构体申明

结构体在这里给了三种声明样式

(1)字典样式的键值对(使用花括号)

(2)元组样式的数值元组(使用圆括号)

(3)空结构体,可以被格式化输出名字

// 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 DONEstruct ColorClassicStruct {// TODO: Something goes herered:u8,green:u8,blue:u8,
}struct ColorTupleStruct(u8,u8,u8);#[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!");}
}

32.结构体的解包

我们可以在一个结构体实例里面使用..otherStruct来对otherStruct里面未被定义的变量原封不动解包到该结构体实例里面

// 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 = 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);}
}

33.类里面的方法除了当前区域内的变量,其他都要加self引用

// 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) -> bool {// Something goes here...return self.sender_country!=self.recipient_country}fn get_fees(&self, cents_per_gram: i32) -> i32 {// Something goes here...return cents_per_gram*self.weight_in_grams}
}#[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);}
}