Classes and objects

Need a help please. I have a program calculating average of students grades:

Code:

---

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


using namespace std;


const int TOTAL_STUDENTS = 10;               
const int TOTAL_GRADES = 10;               


void readInput(fstream *file, string[], int grades[][TOTAL_GRADES]);         
void calcAvg(string names[], int grades[][TOTAL_GRADES], float average[]);   
void printData(string names[], int grades[][TOTAL_GRADES], float average[]); 


int main()
{
  string names[TOTAL_STUDENTS];             
  int grades[TOTAL_STUDENTS][TOTAL_GRADES]; 
  float average[TOTAL_STUDENTS];           
  fstream inputfile;                         
  string fileName;                           


  cout << "Hello there!" << endl;
  cout << "This is a program to calculate students' average test scores" << endl;
  cout << "-------------------------------------------------------------" << endl;


  cout << "Now, enter the file name: "; 
  cin >>  fileName;
  cout << endl;


    inputfile.open(fileName.c_str());


    if(inputfile.is_open())
    {
        readInput(&inputfile, names, grades);
        calcAvg(names, grades, average);
        printData(names, grades, average);
    }
    else
  {
  cout << "Please enter a correct file name or make sure file is in the same directory as the program." << endl;


  return -1;
  }


  inputfile.close();


  return 0;
}


void readInput(fstream *file, string names[], int grades[][TOTAL_GRADES])
{
  for(int i = 0; i < TOTAL_STUDENTS; i++)
    {
    *file >> names[i];
  for(int j = 0; j < TOTAL_GRADES; j++)
    {
      *file >> grades[i][j];
    }
    }
}


void calcAvg(string names[], int grades[][TOTAL_GRADES], float average[])
{
    float sum;
    for(int i = 0; i < TOTAL_STUDENTS; i++)
    {
        sum = 0;
        for(int j = 0; j < TOTAL_GRADES; j++)
        {
      sum += grades[i][j];
        }
        sum = (float)sum/TOTAL_GRADES;
        average[i] = sum;
    }
}


void printData(string names[], int grades[][TOTAL_GRADES], float average[])
{
    for(int i = 0 ; i < TOTAL_STUDENTS; i++)
    {
        cout << names[i] << " ";
        for(int j = 0; j < TOTAL_GRADES; j++)
        {
            cout << grades[i][j] << " ";
        }
        cout << fixed << showpoint << setprecision(2) << average[i] << endl;
    }
}

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I need to re-write this program in classes. I have header file:

Code:

---

#ifndef STUDENTTYPE_H
#define STUDENTTYPE_H
#include <iomanip>


const int TOTAL_STUDENTS = 10;
const int TOTAL_GRADES = 10;


class StudentType
{
  public:
    StudentType();
    readInput(ifstream&):void;
    calcAvg():void;
    printData(ostream&) const:void;
  private:
    string names;
    int grades[TOTAL_GRADES];
    float average;
};


#endif // STUDENTTYPE_H

---

I am OK with main program. But I don't know how the implementation file should look like. Any suggestions please?

Code:

---

#include "StudentType.h"
#include <iostream>




StudentType::StudentType()
{
  name = "";
  for (int i=0; i<TOTAL_STUDENTS; i++)
  {
    grades[i]={0};
  }
  average = 0.0;
}
??????

---

Thank you

You have to implement the functions (actually you have almost the body of them already).
As you implemented the constructor , you shall do the other functions.
I mean you write

Code:

---

StudentType::functionName(parameterList)
{
      /*body of the function*/
      /*because of the operator :: you get access to the private fields of StudentType class*/
}

---

I hope that I understood the problem and this helps :)

I suggest overloading operator>> and operator<< for I/O instead:

Code:

---

class StudentType
{
public:
    StudentType();
    void calculateAverage();
    friend std::istream& operator>>(std::istream& in, StudentType& student);
    friend std::ostream& operator<<(std::ostream& out, const StudentType& student);
private:
    std::string name;
    int grades[TOTAL_GRADES];
    float average;
};

---

Take a look at your previous implementation of readInput. You have this part to read the data for one student:

Code:

---

*file >> names[i];
for(int j = 0; j < TOTAL_GRADES; j++)
{
    *file >> grades[i][j];
}

---

So, all you need to do is to implement operator>> using the same thing, e.g.,

Code:

---

std::istream& operator>>(std::istream& in, StudentType& student)
{
    in >> student.name;
    for (int i = 0; i < TOTAL_GRADES; ++i)
    {
        in >> student.grades[i];
    }
    return in;
}

---

This way, your readInput function becomes:

Code:

---

void readInput(fstream& file, StudentType students[])
{
    for (int i = 0; i < TOTAL_STUDENTS; ++i)
    {
        file >> students[i];
    }
}

---

Notice that I made file an fstream& instead of an fstream*.

Likewise, your calcAvg function will loop over the students and call the calculateAverage member function for each of them (or you can change it such that operator>> will call calculateAverage), and then your printData function will loop over the students and use the operator<< to print each of them.

Thank you, guys. It did help a lot! :)