C++ STL Map_C/C++/C#

源文件
#include 
#include 
#include 
#include 
#include 

using namespace std;



void createMap(){
    //way1
    map m0 ;
    map m1 {{"name","tony"},{"age","20"}};
    // map m1 {make_pair("name","tony"),make_pair("age","20")};
    //way2
    map m2(m1);
    // //way3 C++ 11
    // //创建一个会返回临时 map 对象的函数
    // map disMap(){
    //     std::maptempMap{ {"C语言教程",10},{"STL教程",20} };
    //     return tempMap;
    // }
    // //调用 map 类模板的移动构造函数创建 newMap 容器
    // std::map m3(disMap());
    //way4
    mapm5{ {"C语言教程",10},{"STL教程",20} };
    mapnewMap(++m5.begin(), m5.end());
    //way5 创建容器同时制定排序规则
    std::map m4{ {"C语言教程",10},{"STL教程",20} };
    std::map > m4a{ {"C语言教程",10},{"STL教程",20} };
    //修改排序规则
    std::map > m4b{ {"C语言教程",10},{"STL教程",20} };

}



void printMapValue(pair p){
    cout << p.first << ":" << p.second << "  ";
}
void mapTraverse(){
    map m {{"name","peter"},{"age","19"},{"phone","123456"}};
    //way1
    for (auto it = m.begin();it != m.cend();++it){
        cout << it->first << ":" << it->second << "  ";
    }
    cout << endl;
    //way2
    auto start = m.begin();
    while (start != m.cend())
    {
        cout << start->first << ":" << start->second << "  ";
        start ++;
    }
    cout << endl;
    //way3
    for (auto value : m){
        cout << value.first << ":" << value.second << "  ";
    }
    cout << endl;
    //way4
    for_each(m.crbegin(),m.crend(),printMapValue);
    cout << endl;

    //way5 find()
    // auto it = m.find("age"); //找到相当于begin()
    auto it = m.find("hello"); //没找到就相当于end()
    for (; it != m.end(); it++)
    {                   
        cout << it->first << ":" << it->second<< " ";
    }
    cout << endl;
    //way6 lower_bound(),upper_bound()
    //lower_bound(key) 和 upper_bound(key) 更多用于 multimap 容器，在 map 容器中很少用到。
    //找到第一个键的值不小于 "name" 的键值对
    auto iter = m.lower_bound("name");
    cout << "lower：" << iter->first << " " << iter->second << endl;
    //找到第一个键的值大于 "name" 的键值对
    iter = m.upper_bound("name");
    cout <<"upper：" << iter->first << " " << iter->second << endl;

    
    //创建一个 pair 对象，来接收 equal_range() 的返回值
    pair ::iterator, map::iterator> myPair = m.equal_range("name");
    //通过遍历，输出 myPair 指定范围内的键值对
    for (auto iter = myPair.first; iter != myPair.second; ++iter) {
        cout << iter->first << " " << iter->second << endl;
    }
}

void mapGetValueByKey(){
    map mp ;
    mp["1"] = "C";
    mp["2"] = "C++";
    mp["3"] = "Go";
    mp["4"] = "Ruby";
    for (auto value : mp){
        cout << value.first << ":" << value.second << "  ";
    }
    cout << endl;
    //1)[] 已存在的key为赋值或修改；不存在的key为新增；
    mp["5"] = "Jave";//
    mp["4"] = "Js";
    for (auto value : mp){
        cout << value.first << ":" << value.second << "  ";
    } 
    cout << endl;
    //2）at()
    mp.at("5") = "PHP";
    // mp.at("6") = "C#";//out_of_range
    for (auto value : mp){
        cout << value.first << ":" << value.second << "  ";
    } 
    cout << endl;
    // 3)find()或for循环+迭代器
}

void mapInsert(){
    //1)无需指定插入位置 
    //创建一个空 map 容器
    std::map mp1;
    //创建一个真实存在的键值对变量
    std::pair p1 = { "name","tony" };
    //创建一个接收 insert() 方法返回值的 pair 对象
    std::pair::iterator, bool> ret;
    //插入 p1，由于 p1 并不是临时变量，因此会以第一种方式传参
    ret = mp1.insert(p1);
    cout << "ret.iter = <{" << ret.first->first << ", " << ret.first->second << "}, " << ret.second << ">" << endl;
    //以右值引用的方式传递临时的键值对变量
    ret = mp1.insert({ "age","19" });
    cout << "ret.iter = <{" << ret.first->first << ", " << ret.first->second << "}, " << ret.second << ">" << endl;
    //插入失败样例
    ret = mp1.insert({ "name","tony" });
    cout << "ret.iter = <{" << ret.first->first << ", " << ret.first->second << "}, " << ret.second << ">" << endl;

    //2）指定插入位置
    //创建一个空 map 容器
    std::map mp2;
    //创建一个真实存在的键值对变量
    std::pair p2 = { "name","tony" };
    //指定要插入的位置
    std::map::iterator it = mp2.begin();
    //向 it 位置以普通引用的方式插入 p2
    auto iter1 = mp2.insert(it, p2);
    cout << iter1->first << " " << iter1->second << endl;
    //向 it 位置以右值引用的方式插入临时键值对
    auto iter2 = mp2.insert(it, std::pair("age", "19"));
    cout << iter2->first << " " << iter2->second << endl;
    //插入失败样例
    auto iter3 = mp2.insert(it, std::pair("name", "tony"));
    cout << iter3->first << " " << iter3->second << endl;

    //3)插入指定区域的键值对
    //创建并初始化 map 容器
    std::map mp3{ {"name","tony"},
                                                {"age","19"},
                                                {"phone","123456"} };
    //创建一个空 map 容器
    std::mapcopymap;
    //指定插入区域
    std::map::iterator first = ++mp3.begin();
    std::map::iterator last = mp3.end();
    //将区域内的键值对插入到 copymap 中
    copymap.insert(first, last);
    //遍历输出 copymap 容器中的键值对
    for (auto iter = copymap.begin(); iter != copymap.end(); ++iter) {
        cout << iter->first << " " << iter->second << endl;
    }
    //4)insert()多个pair
    map mp4;
    mp4.insert({{"name","tom"},{"age","17"},{"phone","567890"}});
    for (auto iter = mp4.begin(); iter != mp4.end(); ++iter) {
        cout << iter->first << " " << iter->second << endl;
    }
}


void mapEmplace(){
    //1.emplace()
    //创建并初始化 map 容器
    std::map mp1;
    //插入键值对
    pair::iterator, bool> ret = mp1.emplace("name", "jemmy");
    cout << "1、ret.iter = <{" << ret.first->first << ", " << ret.first->second << "}, " << ret.second << ">" << endl;
    //插入新键值对
    ret = mp1.emplace("age", "15");
    cout << "2、ret.iter = <{" << ret.first->first << ", " << ret.first->second << "}, " << ret.second << ">" << endl;
    //失败插入的样例
    ret = mp1.emplace("name", "jemmy");
    cout << "3、ret.iter = <{" << ret.first->first << ", " << ret.first->second << "}, " << ret.second << ">" << endl;

    //2.emplace_hint()
    //创建并初始化 map 容器
    std::mapmp2;
    //指定在 map 容器插入键值对
    map::iterator iter = mp2.emplace_hint(mp2.begin(),"name", "mary");
    cout << iter->first << " " << iter->second << endl;
    iter = mp2.emplace_hint(mp2.begin(), "age", "16");
    cout << iter->first << " " << iter->second << endl;
    //插入失败样例
    iter = mp2.emplace_hint(mp2.begin(), "name", "mary");
    cout << iter->first << " " << iter->second << endl;
}

int main(){

    //mapTraverse();
    // mapGetValueByKey();
    // mapInsert();
    mapEmplace();
    return 0;
}
C++ STL Map

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