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2 changed files with 30 additions and 44 deletions

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@ -1,30 +1,28 @@
// as_ref_mut.rs // as_ref_mut.rs
// //
// AsRef and AsMut allow for cheap reference-to-reference conversions. Read more // AsRef 和 AsMut 允許進行廉價的引用到引用的轉換。詳細閱讀 https://doc.rust-lang.org/std/convert/trait.AsRef.html 和
// about them at https://doc.rust-lang.org/std/convert/trait.AsRef.html and // https://doc.rust-lang.org/std/convert/trait.AsMut.html。
// https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
// //
// Execute `rustlings hint as_ref_mut` or use the `hint` watch subcommand for a // 執行 `rustlings hint as_ref_mut` 或使用 `hint` 子命令以獲取提示。
// hint.
// I AM NOT DONE // I AM NOT DONE
// Obtain the number of bytes (not characters) in the given argument. // 獲取給定參數中的字節數(不是字符數)。
// TODO: Add the AsRef trait appropriately as a trait bound. // TODO: 適當地將 AsRef trait 作為 trait bound 添加。
fn byte_counter<T>(arg: T) -> usize { fn byte_counter<T>(arg: T) -> usize {
arg.as_ref().as_bytes().len() arg.as_ref().as_bytes().len()
} }
// Obtain the number of characters (not bytes) in the given argument. // 獲取給定參數中的字符數(不是字節數)。
// TODO: Add the AsRef trait appropriately as a trait bound. // TODO: 適當地將 AsRef trait 作為 trait bound 添加。
fn char_counter<T>(arg: T) -> usize { fn char_counter<T>(arg: T) -> usize {
arg.as_ref().chars().count() arg.as_ref().chars().count()
} }
// Squares a number using as_mut(). // 使用 as_mut() 將數字平方。
// TODO: Add the appropriate trait bound. // TODO: 添加適當的 trait bound。
fn num_sq<T>(arg: &mut T) { fn num_sq<T>(arg: &mut T) {
// TODO: Implement the function body. // TODO: 實現函數主體。
??? ???
} }

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@ -1,11 +1,8 @@
// from_into.rs // from_into.rs
// //
// The From trait is used for value-to-value conversions. If From is implemented // From trait 用於值到值的轉換。如果 From 為某個類型正確實現,那麼 Into trait 應該可以反向工作。可以在 https://doc.rust-lang.org/std/convert/trait.From.html 閱讀更多內容。
// correctly for a type, the Into trait should work conversely. You can read
// more about it at https://doc.rust-lang.org/std/convert/trait.From.html
// //
// Execute `rustlings hint from_into` or use the `hint` watch subcommand for a // 執行 `rustlings hint from_into` 或使用 `hint` 子命令來獲取提示。
// hint.
#[derive(Debug)] #[derive(Debug)]
struct Person { struct Person {
@ -13,8 +10,7 @@ struct Person {
age: usize, age: usize,
} }
// We implement the Default trait to use it as a fallback // 我們實現 Default trait以便在提供的字串無法轉換為 Person 物件時用作回退。
// when the provided string is not convertible into a Person object
impl Default for Person { impl Default for Person {
fn default() -> Person { fn default() -> Person {
Person { Person {
@ -24,33 +20,26 @@ impl Default for Person {
} }
} }
// 你的任務是完成此實現,以便讓 `let p1 = Person::from("Mark,20")` 這行代碼可以編譯。請注意,您需要將年齡部分解析為 `usize`,可以使用 `"4".parse::<usize>()` 之類的方法。需要適當處理此操作的結果。
// Your task is to complete this implementation in order for the line `let p1 =
// Person::from("Mark,20")` to compile. Please note that you'll need to parse the
// age component into a `usize` with something like `"4".parse::<usize>()`. The
// outcome of this needs to be handled appropriately.
// //
// Steps: // 步驟:
// 1. If the length of the provided string is 0, then return the default of // 1. 如果提供的字串長度為 0則返回 Person 的默認值。
// Person. // 2. 在字串中找到逗號並進行分割。
// 2. Split the given string on the commas present in it. // 3. 從分割操作中提取第一個元素,並將其用作名字。
// 3. Extract the first element from the split operation and use it as the name. // 4. 如果名字為空,則返回 Person 的默認值。
// 4. If the name is empty, then return the default of Person. // 5. 從分割操作中提取另一個元素,並將其解析為 `usize` 作為年齡。
// 5. Extract the other element from the split operation and parse it into a // 如果在解析年齡時出現錯誤,則返回 Person 的默認值。否則,返回具有結果的實例化 Person 物件。
// `usize` as the age.
// If while parsing the age, something goes wrong, then return the default of
// Person Otherwise, then return an instantiated Person object with the results
// I AM NOT DONE
impl From<&str> for Person { impl From<&str> for Person {
fn from(s: &str) -> Person {} fn from(s: &str) -> Person {
// TODO: Complete the function body
}
} }
fn main() { fn main() {
// Use the `from` function // 使用 `from` 函數
let p1 = Person::from("Mark,20"); let p1 = Person::from("Mark,20");
// Since From is implemented for Person, we should be able to use Into // 由於為 Person 實現了 From因此我們應該能夠使用 Into
let p2: Person = "Gerald,70".into(); let p2: Person = "Gerald,70".into();
println!("{:?}", p1); println!("{:?}", p1);
println!("{:?}", p2); println!("{:?}", p2);
@ -61,29 +50,28 @@ mod tests {
use super::*; use super::*;
#[test] #[test]
fn test_default() { fn test_default() {
// Test that the default person is 30 year old John // 測試默認的 Person 是否是 30 歲的 John
let dp = Person::default(); let dp = Person::default();
assert_eq!(dp.name, "John"); assert_eq!(dp.name, "John");
assert_eq!(dp.age, 30); assert_eq!(dp.age, 30);
} }
#[test] #[test]
fn test_bad_convert() { fn test_bad_convert() {
// Test that John is returned when bad string is provided // 測試當提供錯誤的字串時是否返回 John
let p = Person::from(""); let p = Person::from("");
assert_eq!(p.name, "John"); assert_eq!(p.name, "John");
assert_eq!(p.age, 30); assert_eq!(p.age, 30);
} }
#[test] #[test]
fn test_good_convert() { fn test_good_convert() {
// Test that "Mark,20" works // 測試 "Mark,20" 是否工作
let p = Person::from("Mark,20"); let p = Person::from("Mark,20");
assert_eq!(p.name, "Mark"); assert_eq!(p.name, "Mark");
assert_eq!(p.age, 20); assert_eq!(p.age, 20);
} }
#[test] #[test]
fn test_bad_age() { fn test_bad_age() {
// Test that "Mark,twenty" will return the default person due to an // 測試 "Mark,twenty" 是否會因為解析年齡錯誤回傳默認的 Person
// error in parsing age
let p = Person::from("Mark,twenty"); let p = Person::from("Mark,twenty");
assert_eq!(p.name, "John"); assert_eq!(p.name, "John");
assert_eq!(p.age, 30); assert_eq!(p.age, 30);