功能： 讀取txt檔案資料到陣列中，輸入txt檔案路徑，分隔符，輸出為陣列

#include <iostream>
#include <cstring>
#include <string>
using namespace std;

void ReadDataFromFile(string file_path, vector<Point2f>& data, string pattern)
{
    ifstream fin(file_path);
    string line_info,input_result;
    if(fin)
    {
        while (getline (fin, line_info)) // line中不包括每行的換行符
        {
           vector<string> vectorString;
//            stringstream input(line_info);
//            //依次輸出到input_result中，並存入vectorString中
//            while(input>>input_result)
//                vectorString.push_back(input_result);
//            //convert string to float
//            data.emplace_back(Point2f(atof(vectorString[0].c_str()),atof(vectorString[1].c_str())));

          char * cstr = new char [line_info.length()+1];
          std::strcpy (cstr, line_info.c_str());

          // cstr now contains a c-string copy of str

          char * p = std::strtok (cstr,pattern.c_str());
          while (p!=0)
          {
            vectorString.push_back(p);
            p = std::strtok(NULL,pattern.c_str());
          }

          delete[] cstr;
          data.emplace_back(Point2f(atof(vectorString[0].c_str()),atof(vectorString[1].c_str())));

        }
    }
    else // 沒有該檔案
    {
        cout<<"no such file"<<endl;;
    }
}

int main(void)
{
    string img_0_txt = output_path + "/0.png.txt";
    vector<Point2f> feature_l_2d;
    ReadDataFromFile(img_0_txt, feature_l_2d, " ");
    return 0;
}