I'm having trouble reading in data from a plain-text file using the ifstream object.

[Dyndrilliac]

I am using Microsoft Visual Studio 2013. I have read the page from the CPlusPlus.com tutorial involving file I/O ("Input/output with files") several times, but I still cannot get my code to work. I am feeding the input the correct name of a valid plain-text file which is located in the local directory (the same directory as the *.exe file) but the file always fails to open. I set a breakpoint on line 193 and 196 to try and figure out what the problem was. The ifstream object, called "myfile", shows "Error reading characters of string." in the Locals window and myfile.is_open() evaluates to false. I've also tried invoking the c_str() member function of the fileName string when passing my parameters to the ifstream object's constructor.

#include <fstream>
#include <iomanip>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>

using namespace std;

class Student
{
    public:

        Student(const string newName)
        {
            const vector<string> nameParts = splitString(newName, ' ');

            this->setName(newName);
            this->setLastName(nameParts.at(0));
            this->setFirstName(nameParts.at(1));
            this->setMiddleInitial(nameParts.at(2)[0]);
            this->setDataFileName(this->getFirstName() + this->getLastName() + ".dat");

            if (!this->readScoresFromDataFile())
            {
                cerr << "ERROR: Unable to open student data file." << endl;
            }
        }

        const double            getAvgScore()       { return this->avgScore; }
        const string            getDataFileName()   { return this->dataFileName; }
        const string            getFirstName()      { return this->firstName; }
        const string            getLastName()       { return this->lastName; }
        const double            getMaxScore()       { return this->maxScore; }
        const char              getMiddleInitial()  { return this->middleInitial; }
        const double            getMinScore()       { return this->minScore; }
        const string            getName()           { return this->name; }
        const vector<double>    getScores()         { return this->scores; }

        void setAvgScore(const double newAvgScore)          { this->avgScore = newAvgScore; }
        void setDataFileName(const string newDataFileName)  { this->dataFileName = newDataFileName; }
        void setFirstName(const string newFirstName)        { this->firstName = newFirstName; }
        void setLastName(const string newLastName)          { this->lastName = newLastName; }
        void setMaxScore(const double newMaxScore)          { this->maxScore = newMaxScore; }
        void setMiddleInitial(const char newMiddleInitial)  { this->middleInitial = newMiddleInitial; }
        void setMinScore(const double newMinScore)          { this->minScore = newMinScore; }
        void setName(const string newName)                  { this->name = newName; }
        void setScores(const vector<double> newScores)      { this->scores = newScores; }

    protected:

        bool readScoresFromDataFile(void)
        {
            string line = "";
            vector<double> studentScores = this->getScores();

            ifstream myfile(this->getDataFileName());

            if (myfile.is_open())
            {
                double average = 0, maximum = 0, minimum = 0, score = 0;
                bool firstLoopExecution = true;

                while (getline(myfile, line))
                {
                    score = stod(line);
                    studentScores.push_back(score);
                    average += score;

                    if (firstLoopExecution)
                    {
                        minimum = score;
                        maximum = score;
                        firstLoopExecution = false;
                    }

                    if (score < minimum)
                    {
                        minimum = score;
                    }

                    if (score > maximum)
                    {
                        maximum = score;
                    }
                }

                myfile.close();

                average = average / ((double)studentScores.size());

                this->setMaxScore(average);
                this->setMaxScore(maximum);
                this->setMinScore(minimum);
                this->setScores(studentScores);
            }
            else
            {
                return false;
            }

            return true;
        }

        static const vector<string> splitString(const string &s, char delim, bool ignoreEmptyStrings = true)
        {
            stringstream ss(s);
            vector<string> elems;
            string item = "";

            while (getline(ss, item, delim))
            {
                if (ignoreEmptyStrings)
                {
                    if (!item.empty())
                    {
                        elems.push_back(item);
                    }
                }
                else
                {
                    elems.push_back(item);
                }
            }

            return elems;
        }

    private:

        double avgScore = 0;
        string dataFileName = "";
        string firstName = "";
        string lastName = "";
        double maxScore = 0;
        char middleInitial = 0;
        double minScore = 0;
        string name = "";
        vector<double> scores;
};

int main(int argc, char *argv[])
{
    string line = "", fileName = "";
    vector<Student> students;

    cout << "Enter Name of Data File: ";
    cin >> fileName;
    cout << endl;

    ifstream myfile(fileName, ios_base::in);

    if (myfile.is_open())
    {
        while (getline(myfile, line))
        {
            Student myStudent(line);
            students.push_back(myStudent);
        }

        myfile.close();

        double classAverage = 0, classMinimum = 0, classMaximum = 0;
        bool firstLoopExecution = true;

        cout << fixed << setw(20) << "Student" << "Average" << endl;

        for (Student student : students)
        {
            if (firstLoopExecution)
            {
                classMinimum = student.getMinScore();
                classMaximum = student.getMaxScore();
                firstLoopExecution = false;
            }

            if (student.getMinScore() < classMinimum)
            {
                classMinimum = student.getMinScore();
            }

            if (student.getMaxScore() > classMaximum)
            {
                classMaximum = student.getMaxScore();
            }

            classAverage += student.getAvgScore();

            cout << fixed << setw(20) << setprecision(2) << student.getFirstName() + student.getMiddleInitial() + student.getLastName() << student.getAvgScore() << endl;
        }

        classAverage = classAverage / ((double)students.size());

        cout << endl;
        cout << fixed << setw(20) << setprecision(2) << "Class Average:" << classAverage << endl;
        cout << fixed << setw(20) << setprecision(2) << "Class Maximum:" << classMaximum << endl;
        cout << fixed << setw(20) << setprecision(2) << "Class Minimum:" << classMinimum << endl;
    }
    else
    {
        cerr << "ERROR: Unable to open class data file." << endl;
        return EXIT_FAILURE;
    }

    return EXIT_SUCCESS;
}

[coder777]

In the debug environment the default/current path is not necessarily where the exe is. It is where the project files are.

Try for debugging purposes an absolute path.

Alternatively you can change the default path in your project settings.

[Dyndrilliac]

Thank you very much! Moving my data files and then re-running the program until I found the correct directory where my environment expected to find them solved the problem.