insert例子

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

int main()
{
    map<string,size_t> word_count;
    string word;
    while(cin>>word)
    {
        auto ret=word_count.insert({word,1});
        if(!ret.second)
            ++ret.first->second;
    }
    auto map_it=word_count.begin();
    while(map_it!=word_count.end())
    {
         cout<<map_it->first<<" "<<map_it->second<<endl;
         ++map_it;
    }

    return 0;
}