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Talk is cheap. Show you the code!

#include <iostream>
#include <map>
using namespace std;

int main(){
    map<int,string> student;
    student.insert(map<int,string>::value_type(1,"liMing"));//第一种
    student.insert(pair<int,string>(2,"wanglei"));//第二种
    student[3] = "pang";//第三种

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

    pair<map<int,string>::iterator,bool> insert_pair;
    insert_pair = student.insert(pair<int,string>(1,"zpz"));
    if(insert_pair.second == true)
        cout << "Insert successfully!"<<endl;
    else
        cout << "Insert failure!" <<endl;

    return 0;
}

执行结果：

1 liMing
2 wanglei
3 pang
Insert failure!

上述三种有什么区别呢？

前两种其实都是用insert，没有什么区别，但是和第三种的区别是在数据的插入上涉及集合的唯一性这个概念。即当map中有这个关键字时，insert 操作是无法插入的。但是用数组的方式就会直接覆盖掉原先的数据。

#include <iostream>
#include <map>
using namespace std;

int main(){
    map<int,string> student;
    student.insert(map<int,string>::value_type(1,"liMing"));
    student.insert(pair<int,string>(2,"wanglei"));
    student[3] = "pang";

    map<int,string>::iterator iter;
    for(iter = student.begin();iter != student.end(); ++iter){
        cout << iter->first<<" "<<iter->second<<endl;
    }
    
    student[1] = "zpz";
    map<int,string>::iterator iter2;
    for(iter2 = student.begin();iter2 != student.end(); ++iter2){
        cout << iter2->first<<" "<<iter2->second<<endl;
    }


    return 0;
}