学习Rust编程——Option

// using_options_match.rsuse std::collections::HashMap;fn main() { let mut map = HashMap::new(); map.insert("one", 1); map.insert("two", 2); let incremented_value = match map.get("one") { Some(val) => val + 1, None => 0 }; println!("{}", incremented_value);}// using_options_unwrap.rsuse std::collections::HashMap;fn main() { let mut map = HashMap::new(); map.insert("one", 1); map.insert("two", 2); let incremented_value = map.get("three").unwrap() + 1; println!("{}", incremented_value);}