问C++字符串加倍

EN

$GPRMC,062513.000,A,3645.9487,N,12716.8382,E,1.76,295.08,160116,,,A*6E

#include<iostream>
#include<string>


using namespace std;


//"$GPRMC,062513.000,A,3645.9487,N,12716.8382,E,1.76,295.08,160116,,,A*6E";

int main()
{
    string gps="$GPRMC,062516.000,A,3645.9494,N,12716.8365,E,1.82,302.69,160116,,,A*63";

    int com_1;
    int com_2;
    int com_3;
    int com_4;
    int com_5;
    int com_6;
    int com_7;
    int com_8;
    int com_9;

    string kind;
    string time;
    string state;
    string latitude;
    string n_s;
    string longitude;
    string e_w;
    string knot;
    string degree;

    double Kind;
    double Time;

    double Latitude;

    double Longitude;

    double Knot;
    double Degree;

    com_1=gps.find(",");
    com_2=gps.find(",",com_1+1);
    com_3=gps.find(",",com_2+1);
    com_4=gps.find(",",com_3+1);
    com_5=gps.find(",",com_4+1);
    com_6=gps.find(",",com_5+1);
    com_7=gps.find(",",com_6+1);
    com_8=gps.find(",",com_7+1);
    com_9=gps.find(",",com_8+1);


    kind=gps.substr(0,com_1);
    time=gps.substr(com_1+1,com_2-com_1-1);
    //state=gps.substr(com_2+1,com_3-com_2-1);
    latitude=gps.substr(com_3+1,com_4-com_3-1);
    //n_s=gps.substr(com_4+1,com_5-com_4-1);
    longitude=gps.substr(com_5+1,com_6-com_5-1);
    //e_w=gps.substr(com_6+1,com_7-com_6-1);
    knot=gps.substr(com_7+1,com_8-com_7-1);
    degree=gps.substr(com_8+1,com_9-com_8-1);


    Kind=stod(kind);
    Time=stod(time);
    //State=stod(state);
    Latitude=stod(latitude);
    //N_s=stod(n_s);
    Longitude=stod(longitude);
    //E_w=stod(e_w);
    Knot=stod(knot);
    Degree=stod(degree);