关于c++:C-STL-multimap容器

一、前言

multimap容器和map容器根本相似，在这里只阐明map容器没有的内容，或者与map容器的区别。
和 map 容器的区别在于：multimap 容器中能够同时存储多（≥2）个键雷同的键值对。

二、办法

和 map 容器相比，multimap 未提供 at() 成员办法，也没有重载 [] 运算符。因而这里说一下multimap容器获取值的办法。

1、获取值

1）办法1

std::multimap<int, string> multimap{ {1,"lin"},{1,"wen"},{1, "kai"},{2,"li"},{2,"wu"},{3,"huang"} };    int nCount = multimap.count(1);std::cout << "nCount: " << nCount << std::endl;std::multimap<int, string>::iterator mtmapIter = multimap.begin();for (int i = 0; i < nCount; i++){    std::cout << mtmapIter->first << "  " << mtmapIter->second << std::endl;    ++mtmapIter;}

2）办法2

std::multimap<int, string> multimap{ {1,"lin"},{1,"wen"},{1, "kai"},{2,"li"},{2,"wu"},{3,"huang"} };    int nCount = multimap.count(1);std::cout << "nCount: " << nCount << std::endl;std::multimap<int, string>::iterator mtmapBeginIter = multimap.lower_bound(1);for (; mtmapBeginIter != multimap.upper_bound(1); mtmapBeginIter++){    std::cout << mtmapBeginIter->first << "  " << mtmapBeginIter->second << std::endl;}

3）办法3

std::multimap<int, string> multimap{ {1,"lin"},{1,"wen"},{1, "kai"},{2,"li"},{2,"wu"},{3,"huang"} };    int nCount = multimap.count(1);std::cout << "nCount: " << nCount << std::endl;pair<std::multimap<int, string>::iterator, std::multimap<int, string>::iterator> iter = multimap.equal_range(1);for (; iter.first != iter.second; iter.first++){    std::cout << iter.first->first << "  " << iter.first->second << std::endl;}

后果如下：