C++11新特性学习--容器篇

最新推荐文章于 2024-09-11 08:49:21 发布

Stone_OverLooking

最新推荐文章于 2024-09-11 08:49:21 发布

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分类专栏： C++11 文章标签： c++

本文链接：https://blog.youkuaiyun.com/Stone_OverLooking/article/details/123355245

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本文介绍了C++中map, set, multimap和unordered_set关联容器的使用，展示了它们的特性，如排序、重复值处理和操作演示。重点在于set与multiset的区别，以及unordered_set的无序特性。

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class STLClass
{
public:  //关联容器 排序的 map set 
    static void testMultiSet()  //可以有重复值
    {
        multiset<string> city{"xian","beijing","tianjin","henan","weinan"};
        for(const auto &elem : city)
        {
            cout<<elem<<endl;
        }
        city.insert({"pucheng","fuping","xian"});
        for(const auto &elem : city)
        {
            cout<<elem<<endl;
        }
    }

    static void testSet()  //不允许有重复值
    {
        set<string> city{"xian","beijing","tianjin","henan","weinan"};
        for(const auto &elem : city)
        {
            cout<<elem<<endl;
        }
        city.insert({"pucheng","fuping","xian"}); //新添加的xian会被删除
        for(const auto &elem : city)
        {
            cout<<elem<<endl;
        }
    }

    static void testMultiMap() //元素能重复
    {
        multimap<int ,string> mmap;
        mmap={
            {1,"sss"},{3,"qqq"},{8,"aaa"},{7,"bbb"},{3,"qqq"}
        };
        for(const auto &elem : mmap)
        {
            cout<< elem.first<<":"<<elem.second<<endl;
        }
    }
    static void testMap() //元素不能重复 自动会删除
    {
        map<int ,string> mmap;
        mmap={
            {1,"sss"},{3,"qqq"},{8,"aaa"},{7,"bbb"},{3,"qqq"}
        };
        for(const auto &elem : mmap)
        {
            cout<< elem.first<<":"<<elem.second<<endl;
        }

        map<int ,string>::iterator itor;
        for(itor=mmap.begin();itor!=mmap.end();itor++)
        {
            cout<<"iter:" <<itor->second<<endl;
        }


    }
public: //无序容器 unorderedSet   unorderedMultiSet
    static void testUnorderedSet()
    {
        unordered_multiset<string> city{"xian","beijing","tianjin","henan","weinan"};
        for(const auto &elem : city)
        {
            cout<<elem<<endl;
        }
        city.insert({"pucheng","fuping","xian"});
        for(const auto &elem : city)
        {
            cout<<elem<<endl;
        }

        unordered_multiset<string>::iterator itor;
        for(itor=city.begin();itor!=city.end();itor++)
        {
            cout<<"iter:" <<*itor<<endl;
        }

    }

    static void testUnordered_multimap()
    {
        unordered_multimap<int ,string> mmap;
        mmap={
            {1,"sss"},{3,"qqq"},{8,"aaa"},{7,"bbb"},{3,"qqq"}
        };
    }


};


class PrintInt
{
public:
    void operator()(int elem)
    {
        cout<<elem<<endl;
    }
    //for_each 实现方法
    template<typename Iterator,typename Operation>
    Operation for_each(Iterator act,Iterator end,Operation op)
    {
        while (act!=end)
        {
            op(*act);
            ++act;
        }
        return op;
    }

    static void test()
    {
        vector<int> coll;
        for(int i=0;i<5;i++)
            coll.push_back(i);
        
        //for_each(coll.cbegin(),coll.cend(),PrintInt());
    }
};