算法入门 -- STL 入门学习map

map用于存储健值对的形式的数据。一般是int和string的键值类型，也可和结构体结合。

常见键值对

插入数据一般有三种方法，结合pair，value_type和数组形式的插入。

//
// Created by 29273 on 2021-03-22.
//

#include "bits/stdc++.h"

using namespace std;

int main() {
    map<int, string> mapA;
    // 结合value_type插入数据
    mapA.insert(map<int, string>::value_type(1, "tom"));
    mapA.insert(map<int, string>::value_type(2, "tony"));
    mapA.insert(map<int, string>::value_type(3, "tk"));
    // 结合pair插入数据
    mapA.insert(pair<int, string>(4, "good"));
    mapA.insert(pair<int, string>(5, "god"));
    mapA.insert(pair<int, string>(6, "better"));
    // 数组的形式
    mapA[7] = "whatever";
    // while 循环遍历
    map<int, string>::iterator iter1 = mapA.begin();
    while (iter1 != mapA.end()) {
        cout << " " << iter1->first << " " << iter1->second << endl;
        iter1++;
    }
    map<int, string>::iterator iter2 = mapA.begin();
    // for 循环遍历
    for (; iter2 != mapA.end(); iter2++) {
        cout << " " << iter2->second << " " << iter2->first << endl;
    }
    return 0;
}

与结构体结合

//
// Created by 29273 on 2021-03-22.
//

#include "bits/stdc++.h"

using namespace std;

struct stu {
    string name;
    int age;

    stu(string name, int age) {
        this->name = name;
        this->age = age;
    }
};


int main() {
    map<int, string> mapA;
    map<int, stu> mapB;

    mapB.insert(map<int, stu>::value_type(1, stu("area1", 3)));
    mapB.insert(map<int, stu>::value_type(2, stu("area2", 3)));
    mapB.insert(map<int, stu>::value_type(3, stu("area3", 3)));

    map<int, stu>::iterator iter3 = mapB.begin();
    for (; iter3 != mapB.end(); ++iter3) {
        cout << iter3->first << " " << iter3->second.name << " " << iter3->second.age << endl;
    }

    return 0;
}