摘要： fn main() { let s = String::from("hello, 世界"); let slice1 = &s[0..1]; //提示: `h` 在 UTF-8 编码中只占用 1 个字节 assert_eq!(slice1, "h"); let slice2 = &s[7..=9];/ 阅读全文

摘要： struct Sheep {} struct Cow {} trait Animal { fn noise(&self) -> String; } impl Animal for Sheep { fn noise(&self) -> String { "baaaaah!".to_string() } 阅读全文