C++ Primer 学习笔记——关联容器初识

关联容器中元素按照关键字来访问和保存

map key-value对（字典中单词是key，单词释义是value)——关联数组，

set 只保存关键字

multimap

multiset 允许多个元素具有相同的关键字

map

map<key类型，value类型>

    map<string, size_t> words;
    string word;
    while (cin >> word)
    {
        ++words[word];//word类似数组的下标
    }
    for (auto &s : words)
    {
        cout << s.first << "occurs" << s.second << endl;
        //first保存关键字，second保存值。是pair类的数据成员
    }
           

set

set<key类型>

    map<string, size_t> words;
    set<string> exclude = { "i", "a", "is" };
    string word;
    while (cin >> word)
    {
        if (exclude.find(word) == exclude.end())
        //find()调用返回指向该关键字的迭代器，或者没找到返回尾后迭代器
            ++words[word];
    }
    for (auto &s : words)
    {
        cout << s.first << "occurs" << s.second << endl;
    }
           

//11.4
#include<iostream>
#include<map>
#include<string>
#include<set>
using namespace std;
int main()
{
    map<string, size_t> words;
    set<string> exclude = { "i", "a", "is" };
    string word;
    int index = ;
    while (cin >> word)
    {
        for (auto &s : word)
        {
            s=tolower(s);
            if (ispunct(s))
            {
                s = '\0';//这里还是不对、、、？？？？？？
            }
        }

        if (exclude.find(word) == exclude.end())
            ++words[word];
    }
    for (auto &s : words)
    {
        cout << s.first << "occurs" << s.second << endl;
    }
    return ;
}
           

定义关联容器

map<string, size_t> words;
map<string,string> name={{"af","advs",
                         {"dsvsfda","fsa"}}；
                         //{key,value}构成一个元素
set<string> exclude = { "i", "a", "is" };
           

//11.7
#include<iostream>
#include<string>
#include<map>
#include<vector>
using namespace std;
int main()
{
    map<string, vector<string>> familys = {
        { "shen", {"hongwei","faf"} }
    };
    string xingshi;
    string name1, name2;
    while (cin >> xingshi)
    {
        cin >> name1;
        cin >> name2;
        familys[xingshi].push_back(name1);
        familys[xingshi].push_back(name2);
    }
    for (auto &s : familys)
    {
        vector<string> name;
        name = s.second;
        for (auto &c : name)
            cout << s.first << " " << c << " " << endl;
    }
    return ;

}