Boltzmann Fit in C++ with ROOT Cern

#include <iostream>
#include <conio.h>
#include <TApplication.h>
#include <TF1.h>
#include <TMath.h>
#include <string>
#include <TCanvas.h>
#include <TGraph.h>
#include <TAxis.h>
#include <TGraphErrors.h>
#include <TLegend.h>
#include <TStyle.h>

#include <vector>
#include <algorithm>
#include <fstream>
#include <sstream>

using namespace std;

template<typename T>
T StringToNumber(const std::string& numberAsString)
{
    T valor;

    std::stringstream stream(numberAsString);
    stream >> valor;
    if (stream.fail()) {
        std::runtime_error e(numberAsString);
        throw e;
    }
    return valor;
}

double Boltzmann(double* x, double* par){
    // Boltzmann equation
    Double_t xx = x[0];
    Double_t A1 = par[0];
    Double_t A2 = par[1];
    Double_t x0 = par[2];
    Double_t dx = par[3];

    return (par[0] - par[1])/(1+exp(xx-par[2])/par[3]) + par[1];
}

struct data
{
    int rows;
    int colunms;
    vector<string> items;
};

data readData(string fileloc){
    cout << "Read in Date from File: " << fileloc << endl;
    ifstream inputFile(fileloc);
    string line;
    string temp;
    stringstream iss;
    vector<string> items;
    int rows = 0;
    int colnms = 0;
    while (getline(inputFile, line, '\n')) // Standard is \n...
    {
        iss << line;
        while (getline(iss, temp, '\t')){
            items.push_back(temp);
            colnms++;
        }
        iss.clear();
        rows++;
    }

    colnms = colnms/rows;

    cout << "Reihen: " << rows << endl;
    cout << "Spalten: " << colnms << endl << endl;

    data retVal = {rows, colnms, items};



    return retVal;
}

int main(int argc, char **argv){

    /*
        Read in DATA - tab is delimiter, be careful with your data (there has to be a \t before \n)
    */

    data Data = readData("data.dat");

    vector<double> tempature;
    vector<double> R_s;
    vector<double> sigR_s;

    tempature.reserve(Data.rows);
    R_s.reserve(Data.rows);
    sigR_s.reserve(Data.rows);


    double temp1,temp2,temp3 = 0;
    for(unsigned int i = 0; i < Data.items.size(); ++i){
        if((i % 3) == 0){
            temp1 = StringToNumber<double>(Data.items[i]);
            //cout << "temp1: " << temp1 << endl;
            tempature.push_back(temp1);
        } else if ((i % 3) == 1){
            temp2 = StringToNumber<double>(Data.items[i]);
            //cout << "temp2: " << temp2 << endl;
            R_s.push_back(temp2);
        } else if ((i % 3) == 2) {
            temp3 = StringToNumber<double>(Data.items[i]);
            //cout << "temp3: " << temp3 << endl;
            sigR_s.push_back(temp3);
        } else {
            cout << "Something weird happens!";
        }
        temp1, temp2, temp3 = 0;
    }


    /*
        Plot and Fit data
    */

    double* Atemperature = &tempature[0];
    double* AR_s = &R_s[0];
    double* AsigR_s = &sigR_s[0];

    TApplication theApp("App",&argc,argv);

    TCanvas* can1 = new TCanvas("Squid Resistance", "Squid Resistance",0 ,0 ,900 , 650);
    can1->SetGridx(1);
    can1->SetGridy(1);

    TGraphErrors* errorgraph1 = new TGraphErrors(R_s.size(), Atemperature, AR_s, NULL, AsigR_s);
    errorgraph1->SetTitle("Squid Resistance");
    errorgraph1->GetXaxis()->SetTitle("Temperature [K]");
    errorgraph1->GetYaxis()->SetTitle("Squid Resistance");
    errorgraph1->SetMarkerStyle(kFullCircle);
    errorgraph1->SetMarkerColor(kMagenta);


    TF1* frenMittel = new TF1("BoltzmannEq", Boltzmann, 70, 150, 4);
    frenMittel->SetLineColor(kRed);
    frenMittel->SetParameters(12.19297,67.16567,98.93677,0.59634);
    frenMittel->SetParNames("A1", "A2", "x0", "dx");
    errorgraph1->Fit("BoltzmannEq");
    errorgraph1->Draw("AP");

    gStyle->SetOptFit(1111);

    //TLegend* leg = new TLegend(0, 1, 0.3, 0.8);
    //leg->SetHeader("Legend");
    //leg->AddEntry(errorgraph1, "Data", "ep");
    //leg->AddEntry(frenMittel, "Fit", "l");
    //leg->Draw();


    can1->Update();




    theApp.Run();
    return 0;
}