c++ - 为什么这段代码在 ROOT 下编译，但没有做任何它想做的事情？

Question

我正在尝试编写一段代码来执行以下任务:

1. 读入包含几年(1722 年到 2013 年)平均每日温度的数据文件
2. 求出年平均气温
3. 制作这些年平均温度的直方图
4. 通过这些数据进行拟合，以便在给定特定年份(例如 2060 年)的情况下，您可以推断以确定该年的平均温度。

到目前为止我写的代码，包括在下面，应该能够执行任务 1 到 3。它分为四个部分:一个头文件“sketch.h”，一个 C++ 脚本“sketch.cpp” "、另一个 C++ 脚本“project.cpp”和一些 ROOT 绘图文件“rootlogon.C”。

文件“sketch.h”和“sketch.cpp”包含类的定义及其成员的实现。“project.cpp”是实例化分析对象的文件。 “rootlogon.C”对直方图和图形的外观有一些预定义的偏好。

想法是，如果 ROOT 在包含这 4 段代码的同一文件夹中运行，它将自动加载它们。

草图.h

#ifndef TEMPTRENDER_H
#define TEMPTRENDER_H

#include <string>

class tempTrender 
{
public:
tempTrender(std::string filePath); //Construct using the specified filePath


//void tempPerYear(int yearToExtrapolate); //Make a histogram of average temperature per year, then fit and extrapolate to the given year

void read_datFile();  //will be used to read in the data file

private:
std::string pathToFile;   //my uppsala .dat file

int Year;
int Month;
int Day;
double Temp_exp;
double Temp_corr;
int dat_ID;

std::string helpString;
std::string filePath;

int numEntries; //total number of measurements done (entries in the data set)

int totTemp; //sum of daily temperatures in a given year
int counter;
int first_Year; //the year in which the measurements began
double AvgTemp; //average annual temperature

};

#endif

草图.cpp

#include <iostream>
#include "sketch.h"
#include <fstream>
#include <string>
#include <sstream>

//ROOT library objects
#include <TF1.h> // 1d function class
#include <TH1.h> // 1d histogram classes
#include <TH2.h> // 2d histogram classes
#include <TRandom.h> // random generators
#include <TStyle.h>  // style object
#include <TMath.h>   // math functions
#include <TCanvas.h> // canvas object
#include <TGraph.h>  //For the graphs part
#include <TLegend.h>  //for the legends

using namespace std;


tempTrender::tempTrender(string filePath)
{
std::cout << "The user supplied " << filePath << " as the path to the data file." << endl;
string pathToFile = filePath;
}

//reading in data file
void tempTrender::read_datFile()
{
ifstream datFile(filePath.c_str());   //opening data file, as a C-string for later manipulation

if(!datFile) cout<<"Error: the file could not be read"<<endl; //just checking if the file was read in successfully ;-)

int n = 0; //initialise a counter
while(getline(datFile, helpString)) n++; //counting the number of lines in the data set;
numEntries = n;

//returning to the beginning of .dat file
datFile.clear();
datFile.seekg(0, ios::beg);


for(int i=0; i<numEntries; i++)
{
datFile >> Year >> Month >> Day >> Temp_exp >> Temp_corr >> dat_ID; //putting input data into categories
    std::cout<<Year<<endl; //checking that the categories contain the right data
    std::cout<<"I'm alive"<<endl;
}

//calculating average temperature and creating a histogram of the values

TH1F* hAvgTemp = new TH1F("hAvgTemp", "Average Annual Temperature: 1722-2013" , 600, 1722, 2013);

    while(datFile>> Year >> Month >> Day >> Temp_exp >> Temp_corr >> dat_ID)
    {
        while(first_Year == 1722 && Year == first_Year)
        {
            for(int Month=0; Month < 13; Month++) //loop over every month
            {
                for(int Day =0; Day < 32; Day++) //loop over every day
                {
                    counter++; //count the number of measurements
                    totTemp += Temp_corr;  //sum up the daily temperatures over all months of first_Year
                    AvgTemp = (totTemp/counter); //average temperature for first_Year. One number.
                }
            }
            hAvgTemp->Fill(AvgTemp); //start filling a histogram with the average temperatures
            cout << AvgTemp << endl; //show that the calculation worked
        }
        first_Year = first_Year + 1; //go to the next year and run the loop again
    }

    //creating canvas for hAvgTemp histogram
    TCanvas* c2 = new TCanvas("c1", "hAvgTemp Canvas", 900, 600);
    hAvgTemp->SetMinimum(0);
    hAvgTemp->Draw();
    c2->SaveAs("AvgTemp.png");
   }

项目.cpp

#include "sketch.h"
#include <string>
#include <iostream>

using namespace std;

void project()
{
string pathToFile = "path_to_datFile.dat"; //path to data file
tempTrender t(pathToFile); //Instantiate analysis object
//t.tempPerYear(2050);
}

根登录.C

void rootlogon() {
gStyle->SetOptStat(0); //Let's make our plots look a bit better. Get rid of the stat box
gStyle->SetOptTitle(0); //Get rid of the title (good plots use legends instead)
gStyle->SetTitleSize(0.05, "x"); //Use bigger text on the axes
gStyle->SetTitleSize(0.05, "y");
gStyle->SetLabelSize(0.05, "x"); //Use bigger labels too
gStyle->SetLabelSize(0.05, "y");
gStyle->SetPadTopMargin(0.05); //Change the margins to fit our new sizes
gStyle->SetPadRightMargin(0.05);
gStyle->SetPadBottomMargin(0.16);
gStyle->SetPadLeftMargin(0.16);

gROOT->ProcessLine(".L sketch.cpp+"); //Load the classes that we want to use automatically - Convenient!
gROOT->ProcessLine(".L project.cpp+"); //The + means to recompile only if it changed since last time
}

数据文件提取

我在下面包含了我正在分析的数据文件的摘录。列分别为:年、月、日、测量温度、校正温度和数据 ID。

1722  1 12   1.9   1.8 1
1722  1 13   2.3   2.2 1
1722  1 14   1.8   1.7 1
1722  1 15    .9    .8 1
1722  1 16  -1.8  -1.9 1
.      .     .      .
2013 12 29   3.8   3.6 1
2013 12 30   1.6   1.4 1
2013 12 31   3.3   3.1 1

代码在 ROOT 中编译，但不执行任何其他操作。我已经尝试了很长时间，但没有成功，以弄清楚它出了什么问题。任何帮助将不胜感激。此外，对于如何处理任务 4 的提示也将不胜感激。我是C++新手，欢迎批评。

Answer 1

要让 rootlogon.C 脚本真正执行某些操作，您需要调用一个函数。我相信您想执行名为 project() 的“main”函数。如果是这种情况，那么您需要这样修改您的 rootlogon.C:

void rootlogon() {

// ...

gROOT->ProcessLine(".L sketch.cpp+"); //Load the classes that we want to use automatically - Convenient!
gROOT->ProcessLine(".L project.cpp+"); //The + means to recompile only if it changed since last time

project(); // <- Add this line
}

gROOT->ProcessLine(".L ...") 指令只是编译代码并加载 ROOT 中的库，但您仍然需要调用该函数。