rust map

BTreeMap是有序的,HashMap是无序的

fn testHashMap(){
    use std::collections::BTreeMap;
    use std::collections::HashMap;
    let mut bMap = BTreeMap::new();
    bMap.insert(3,"a");
    bMap.insert(2,"b");
    bMap.insert(1,"c");
    println!("{:?}",bMap);
    println!("bMap[1]:{}",bMap[&1]);
    let mut hMap = HashMap::new();
    hMap.insert(3,"a");
    hMap.insert(2,"b");
    hMap.insert(1,"c");
    println!("{:?}",hMap);
    println!("hMap[2]:{}",hMap[&2]);
}

{1: "c", 2: "b", 3: "a"}
bMap[1]:c
{1: "c", 3: "a", 2: "b"}
hMap[2]:b