modify name

void existnum:: modifyname(string nam)
{
    fstream fin,fout;
    fin.open("file1.csv",ios::in);
    fout.open("file2.csv",ios::out | ios::app);
    vector<string>row;
    string line,word,temp;
    int cnt=0;
    while(getline(fin,line))
    {
        row.clear();
       // getline(fin,line);
        stringstream s(line);
        while(getline(s,word,','))
        {
            row.push_back(word);
        }
        if(nam==row[0]){
            cnt=1;
            cout<<"Enter the Modified Name"<<endl;
            string newname;
            cin>>newname;
            fout<<newname<<","<<row[1]<<endl;
        //break;9
        }
        else
        {
            fout<<row[0]<<","<<row[1]<<endl;
        }
    }
    fin.close();
    fout.close();
    remove("file1.csv");
    rename("file2.csv","file1.csv");
}