C++でスペース区切りのデータを連想配列に詰め込む

test.dat

1 2
1 3
1 5
3 5
2 4

 #include<stdio.h>
 #include<iostream>
 #include<map>
 #include<string>
 #include<fstream>


 int main(){
         using namespace std;
         FILE *fp;
         std::string index;
         std::string value;
         std::string str;
         char* str2;
         std::map<std::string,std::string> data;
         std::ifstream ifs("test.dat");

         while(ifs && getline(ifs,str)){


                 str=strtok(const_cast<char*>(str.c_str())," ");

                 str2=strtok(NULL," ");
                 data[str]=str2;

         }
         map<string,string>::iterator it=data.begin();
         while(it!=data.end()){

                 cout << (*it).first <<" "<< (*it).second << endl;
                 ++it;
         }

         return 0;
 }

2列目の和を求める。

#include<stdio.h>
#include<iostream>
#include<map>
#include<string>
#include<fstream>


int main(){
        using namespace std;
        FILE *fp;
        std::string index;
        std::string value;
        std::string str;
        int str2;
        std::map<std::string,int> data;
        std::ifstream ifs("test.dat");

        while(ifs && getline(ifs,str)){


                str=strtok(const_cast<char*>(str.c_str())," ");

                str2=atoi(strtok(NULL," "));
                data[str]=data[str]+str2;
                /*
                if(data.find(str)!=data.end()){
                        data[(str)]=str2+data[(str)];
                }else{

                        data[(str)]=str2;

                }
                */


        }
        map<string,int>::iterator it=data.begin();
        while(it!=data.end()){

                cout << (*it).first <<" "<< (*it).second << endl;
                ++it;
        }

        return 0;
}