2021-03-24から1日間の記事一覧
use std::collections::HashMap; #[derive(Debug)] struct A { fields: Option<HashMap<i32, String>>, } impl A { fn get(&self, key: i32) -> Option<&String> { if let Some(ref fields) = self.fields { if let Some(value) = fields.get(&key) { //return Some(value.clone()</hashmap<i32,>…