将命令行参数输入文件传递给类以进行解析

Question

There is probably a very simple solution to my problem but I am having some problems passing an input file (from command line arguments) into a class for parsing.

Here is the relevant part of my main.cpp code:

#include <iostream>
#include <chrono>
#include "SortingCompetition.h"

int main(int argc, char** argv)
{
    if (argc != 3)
    {
        std::cerr << "Invalid arguments" << std::endl;
        std::cerr << "Usage: ./a.out <input file> <output file>" << std::endl;
        return 1;
    }

    SortingCompetition sorter(argv[1]);

    return 0;
}

Here is the SortingCompetition.h file:

#ifndef SORTINGCOMPETITION_H_
#define SORTINGCOMPETITION_H_

#include <string>
#include <vector>
using namespace std;

class SortingCompetition{
private:
    string& input_;
    vector<string> data_;
public:
    SortingCompetition(const string& inputFileName);
    void setFileName(const string& inputFileName);
    bool readData();
    bool prepareData();
    void sortData();
    void outputData(const string& outputFileName);
};

#endif

All the functions must remain the same here. ie SortingCompetition(const string& inputFileName); must stay that way... I cannot remove the const or anything else.

Here is the relevant implementation of SortingCompetition:

#include "SortingCompetition.h"

SortingCompetition::SortingCompetition(const string& inputFileName){
    input_ = inputFileName;
}
void SortingCompetition::setFileName(const string& inputFileName){
    input_ =  inputFileName;
}

This is where I'm getting problems, I'm not passing the input file from the command argument to the private variable correctly. I've searched for quite a while, but cannot find a solution.

Answer 1

You're passing it correctly, but you're storing a reference to temporary. This is the problem.

Change:

class SortingCompetition{
private:
    string input_;  // THIS LINE
    vector<string> data_;

This copies the value so it doesn't matter that the parameter to the constructor (or setFilename ) was only a temporary