[数据结构与算法]【STL map】map multimap

map

红黑树实现-红黑树算法和应用(更高级的二叉查找树)
map 存储的是 pair 对象
按照key的大小 按照既定规则排序(默认是升序排序)

• std::make_pair
• insert
• emplace 插入
• 遍历
• [] 获取元素 找不到为 该类型的默认值 string “” int 0
• 重复的就是更新

  user.insert(  user.begin(),std::make_pair("STL教程","http://baidu.com"));

insert

 user.insert(  user.begin(),std::make_pair("STL教程","http://baidu.com"));
 
 pair<map<string,string>::iterator, bool>  temp = user.emplace(std::make_pair("STL教程", "http://baidu.com"));
 temp -> <iterator,bool>
 
 bool flag = temp.second;
 false

emplace

 string str = "Lionel";
    if (user.find(str) == user.end())
    {
        printf("can not found.");
    }
    printf("exist");

find

    for (auto i = user.begin(); i != user.end(); ++i) {
        printf("%s--%s \n", i->first.c_str(), i->second.c_str());
    }
    OR
       for (auto i = user.begin(); i != user.end(); ++i) {
        cout << i->first << " " << i->second << endl;
    }
这么写会错
  for (auto i = user.begin(); i != user.end(); ++i) {
      
        printf("%s--%s \n", i->first, i->second);
    }

遍历

map可以这样，multimap就不行。

map<string, string> user;
multimap<string, string>user_m;

 user["c"] = "Lionel";
 //user_m["c"] = "Lionel";

multimap

multimap可以存储重复key的pair

    string name[6] = { "a","a" ,"b","c","d","e"};
    string password[6] = { "12345" ,"00909","kitty","bitch","7890","6789"};
    
    for (int i = 0;i < 5;i++)
    {
        user_m.insert(make_pair(name[i],password[i]));
    }

或者

    string name[6] = { "a","a" ,"b","c","d","e"};
    string password[6] = { "12345" ,"00909","kitty","bitch","7890","6789"};
    
    for (int i = 0;i < 5;i++)
    {
        user_m.insert(pair<string, string >(name[i],password[i]));
    }