C++ 关联容器

map

• map能够存储<key, value>对的信息
• C++primer 5th练习11.7
• 输入字符串，忽略大小写和点

• 代码

  #include<iostream>#include<exception>#include<fstream>#include<sstream>#include<string>#include<vector>#include<iterator>#include<list>#include<deque>#include<stack>#include<queue>#include<concurrent_priority_queue.h>#include<algorithm>#include<numeric>#include<functional>  //bind#include<map>using namespace std;bool Smaller(const int &a, const int &b){    return a <= b;}int main(){    cout << "start!" << endl;    map<string, size_t> word_cnt;    string bword, aword;    while (cin >> bword)    {        aword.clear();        for (auto iter = bword.begin(); iter != bword.end(); iter++)        {            if (*iter != '.')            {                aword.push_back(tolower(*iter));            }        }        ++word_cnt[ aword ];    }    for (const auto &w : word_cnt)    {        cout << w.first << " occurs " << w.second << " times" << endl;    }    cout << "end!" << endl;    system("pause");    return EXIT_SUCCESS;}

• insert的使用

  • 可以插入pair的数据类型
  • 如果插入的key之前容器中已经有的话，则插入失败
  • 如果每个<key,value>的first值无法修改，second值可以修改。

  • 代码

    #include<iostream>#include<exception>#include<fstream>#include<sstream>#include<string>#include<vector>#include<iterator>#include<list>#include<deque>#include<stack>#include<queue>#include<concurrent_priority_queue.h>#include<algorithm>#include<numeric>#include<functional>  //bind#include<map>#include<set>using namespace std;int main(){    cout << "start!" << endl;    map<string, string> aus = { {"11", "22"},                                {"33", "44"}};    aus.insert(pair<string,string>("55", "66"));    aus.insert(pair<string, string>("55", "77"));    auto m = aus.begin();    //m->first = "sdddd";    m->second = 455;    cout << "end!" << endl;    system("pause");    return EXIT_SUCCESS;}

set

• set可以存储非重复的元素
• multiset可以存储重复元素
• set和multiset是按照一定的存储顺序存储的

• 代码

  #include<iostream>#include<exception>#include<fstream>#include<sstream>#include<string>#include<vector>#include<iterator>#include<list>#include<deque>#include<stack>#include<queue>#include<concurrent_priority_queue.h>#include<algorithm>#include<numeric>#include<functional>  //bind#include<map>#include<set>using namespace std;bool Smaller(const int &a, const int &b){    return a <= b;}int main(){    cout << "start!" << endl;    vector<int> vi;    for (int i = 0; i < 10; i++)    {        vi.push_back( i );        vi.push_back(i);    }    set<int> si(vi.begin(), vi.end());    multiset<int>  msi(vi.begin(), vi.end());    cout << vi.size() << endl;    cout << si.size() << endl;    cout << msi.size() << endl;    cout << "end!" << endl;    system("pause");    return EXIT_SUCCESS;}

pair

• pair可以存储两组数据成员。
• 这个例子是在C++primer 5th的练习11.12

• 代码

  #include<iostream>#include<exception>#include<fstream>#include<sstream>#include<string>#include<vector>#include<iterator>#include<list>#include<deque>#include<stack>#include<queue>#include<concurrent_priority_queue.h>#include<algorithm>#include<numeric>#include<functional>  //bind#include<map>#include<set>using namespace std;int main(){    cout << "start!" << endl;    vector<pair<string, int>> vp;    int index = 0;    int num;    string str;    string input;    while (cin >> input)    {        if (index == 0)        {            str = input;            index++;        }        else        {            num = atoi(input.c_str());            vp.push_back(pair<string, int>(str, num));            index = 0;        }    }    for (int i = 0; i < vp.size(); i++)    {        cout << "first : " << vp[i].first << ", second : " << vp[i].second << endl;    }    cout << "end!" << endl;    system("pause");    return EXIT_SUCCESS;}