STL的基本使用之关联容器：map和multiMap的基本使用

STL的基本使用之关联容器：map和multiMap的基本使用

1. 简介

   • map 和 multimap 内部也都是使用红黑树来实现，他们存储的是键值对，并且会自动将元素的key进行排序。两者不同在于map 不允许key重复，而multiSet 允许key重复

2. 头文件 #include< map >

3. 构造函数及析构函数

4. 非变动性操作函数

   • 运算符重载
   • 下标运算符
   • 查找操作函数
   • 赋值操作
   • 迭代器操作

5. 插入删除操作

6. 范例如下

    #include <iostream>
    #include <map>
    #include <iomanip>
    using namespace std;
    int main ()
    {
    
    #pragma mark - 基本使用
    map<int,string> c;
    c.insert(make_pair(1,"1")); c.insert(make_pair(2,"2"));
    c.insert(make_pair(4,"4")); c.insert(make_pair(5,"5"));
    c.insert(make_pair(6,"6"));
    
    cout << "lower_bound(3): "  << c.lower_bound(3)->second << endl;
    cout << "upper_bound(3): " << c.upper_bound(3)->first << endl;
    cout << "equal_range(3): "
    << (c.equal_range(3).first)->first << " "
    << (c.equal_range(3).second)->first << endl;
    cout << endl;
    cout << "lower_bound(5): "  << c.lower_bound(5)->first << endl;
    cout << "upper_bound(5): " << c.upper_bound(5)->first << endl;
    cout << "equal_range(5): "
    << (c.equal_range(5).first)->first << " "
    << (c.equal_range(5).second)->first << endl;
    
    c.insert(c.lower_bound(3), make_pair(3, "3"));
    //    c.erase(4);
    c.erase(c.find(4));
    map<int,string>::iterator i;
    for (i = c.begin(); i!=c.end(); i++) {
        cout<<i->first<<" ";
    }
    cout<<endl;
    
    #pragma mark-   实例1：将map当做关联数组
    typedef map<string,float> StringFloatMap;
    StringFloatMap stocks;      // create empty container
    
    //insert some elements
    stocks["BASF"]	= 369.50;
    stocks["VW"]	= 413.50;
    stocks["Daimler"]	= 819.00;
    stocks["BMW"]	= 834.00;
    stocks["Siemens"]	= 842.20;
    
    //print all elements
    StringFloatMap::iterator pos;
    for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
        cout << "stock: " << pos->first << "\t"
        << "price: " << pos->second << endl;
    }
    cout << endl;
    //boom (all prices doubled)
    for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
        pos->second *= 2;
    }
    
    //print all elements
    for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
        cout << "stock: " << pos->first << "\t"
        << "price: " << pos->second << endl;
    }
    cout << endl;
    
    /*rename key from "VW" to "Volkswagen"
     *-only provided by exchanging element
     */
    stocks["Volkswagen"] = stocks["VW"];
    stocks.erase("VW");
    
    //print all elements
    for (pos = stocks.begin(); pos != stocks.end(); ++pos) {
        cout << "stock: " << pos->first << "\t"
        << "price: " << pos->second << endl;
    }
    
    
    
    #pragma mark - 实例2：将multimap当做字典
    typedef multimap<string,string> StrStrMMap;
    //create empty dictionary
    StrStrMMap dict;
    
    //insert some elements in random order
    dict.insert(make_pair("day","Tag"));
    dict.insert(make_pair("strange","fremd"));
    dict.insert(make_pair("car","Auto"));
    dict.insert(make_pair("smart","elegant"));
    dict.insert(make_pair("trait","Merkmal"));
    dict.insert(make_pair("strange","seltsam"));
    dict.insert(make_pair("smart","raffiniert"));
    dict.insert(make_pair("smart","klug"));
    dict.insert(make_pair("clever","raffiniert"));
    
    //print all elements
    StrStrMMap::iterator pos1;
    cout.setf (ios::left, ios::adjustfield);
    cout << ' ' << setw(10) << "english "
    << "german " << endl;
    cout << setfill('-') << setw(20) << ""
    << setfill(' ') << endl;
    for (pos1 = dict.begin(); pos1 != dict.end(); ++pos1) {
        cout << ' ' << setw(10) << pos1->first.c_str()
        << pos1->second << endl;
    }
    cout << endl;
    
    //print all values for key "smart"
    string word("smart");
    cout << word << ": " << endl;
    
    for (pos1 = dict.lower_bound(word);
         pos1 != dict.upper_bound(word); ++pos1) {
        cout << " " << pos1->second << endl;
    }
    
    //print all keys for value "raffiniert"
    word = ("raffiniert");
    cout << word << ": " << endl;
    for (pos1 = dict.begin(); pos1 != dict.end(); ++pos1) {
        if (pos1->second == word) {
            cout << " " << pos1->first << endl;
        }
    }
   

   }

7. 运行截图