study_rust_example/common_collection/
hash_map_study.rs

1use std::collections::{hash_map, HashMap};
2
3#[derive(Eq, Hash, PartialEq, Debug)]
4enum CoinEnum {
5    BTC,
6    ETH,
7    USDT,
8}
9#[derive(Debug)]
10struct CoinProerty {
11    decimal: u32,
12}
13
14fn iterator_hash_map(map_val: &HashMap<CoinEnum, CoinProerty>) {
15    for (key, val) in map_val {
16        println!("key {:?} val {:?}", key, val);
17    }
18}
19
20fn count_text_num(str_val: &str, target: &str) -> u16 {
21    let mut count_map: HashMap<&str, u16> = HashMap::new();
22    for word in str_val.split_whitespace() {
23        let count = count_map.entry(word).or_insert(0);
24        *count += 1;
25    }
26    match count_map.get(target) {
27        None => 0,
28        Some(val) => *val,
29    }
30}
31
32pub fn hash_map_usage_study() {
33    let mut coinMap: HashMap<CoinEnum, CoinProerty> = HashMap::new();
34    coinMap.insert(CoinEnum::BTC, CoinProerty { decimal: 8 });
35    coinMap.insert(CoinEnum::ETH, CoinProerty { decimal: 9 });
36    coinMap.insert(CoinEnum::ETH, CoinProerty { decimal: 18 });
37    coinMap.insert(CoinEnum::USDT, CoinProerty { decimal: 6 });
38    // 检查map是否存在
39    coinMap
40        .entry(CoinEnum::USDT)
41        .or_insert(CoinProerty { decimal: (6) });
42    // 读取hash操作
43    let coin = CoinEnum::ETH;
44    let eth_pro = coinMap.get(&coin);
45    println!();
46    println!("coin {:?}, pro {:?}", coin, eth_pro);
47    iterator_hash_map(&coinMap);
48    let text = "hello hello world rust people hello  hello .";
49    let count = count_text_num(text, &text[..5]);
50    println!("word {} count {}", &text[..5], count);
51}
study_rust_example/common_collection/hash_map_study.rs

study_rust_example/common_collection/
hash_map_study.rs
