fn main() {// 1. 创建字符串let s1 = String::new();let s2 = String::with_capacity(100);let s3 = String::from("hello");let s4 = "RUST".to_string();let s5: String = "rust".into();let s6 = "学习rust".repeat(2);let s7 = String::from_utf8(vec![b'h', b'i']).unwrap();println!("s7 = {}", s7); // hi// 2. 长度let len: usize = s6.len(); // 字节数let char_count: usize = s6.chars().count();let is_empty = s7.is_empty();println!("s6 len({}), chars({}), is empty: {}", len, char_count, is_empty); // s6 len(20), chars(12), is empty: false// 3. 包含、查找let has_u: bool = s5.contains("u");let starts: bool = s5.starts_with("ru");let ends: bool = s5.ends_with("st");let find_llo: Option<usize> = s3.find("llo"); // Some(2)let find_l: Option<usize> = s3.rfind("l"); // Some(3)println!("{}, {}, {}, {:?}, {:?}", has_u, starts, ends, find_llo, find_l); // true, true, true, Some(2), Some(3)// 4. 比较let eq_ignore_case = s4.eq_ignore_ascii_case("rust");println!("{} = {} : {}", s4, "rust", eq_ignore_case); // RUST = rust : true// 5. 修改let mut s = String::from("hello");s.push(','); // push chars.push_str("Rust");s.extend("字符串!".chars());s.insert(5, ',');s.insert_str(6, "world");s.replace_range(0..2, "HEL");let mut sp: String = s.replace("R", "r");let right_char: Option<char> = sp.pop();let src: char = s.remove(7);sp.truncate(6);println!("s: {s}\nsp: {sp}\nright_char:{right_char:?}, s remove char: {src}");sp.retain(|c| c!='H');println!("sp :{}", sp);// s: HELllo,orld,Rust字符串!// sp: HELllo// right_char:Some('!'), s remove char: w// sp :ELllolet mut s8 = " rust!! ".to_string();let trimed: &str = s8.trim();let left_trimed: &str = s8.trim_start();let right_trimed: &str = s8.trim_end();let trimmed_matches: &str = s8.trim_matches(|c| c == '!' || c == ' ');println!("trimed:{}, left_trimed:{}, right_trimed: {}, trimed_matched: {}", trimed, left_trimed, right_trimed, trimmed_matches);// trimed:rust!!, left_trimed:rust!! , right_trimed: rust!!, trimed_matched: rust}
