C++ convert struct to class

[silver11235]

Hello, I just want to have couple question about this code, I am currently converting a struct to class. Problem is I have never encounter writing a program with I/O in the class. I am intend to create a function of public class to read write all the data into private class members. But is it better to use constructor to doing that

This is my original struct code

  #include <iostream>
#include <string>
#include <iomanip>
#include <fstream>
using namespace std;

#define a_row 10
#define a_col 6

ifstream inputname, inputscore;

struct studentRecord
{
	string name;
	int grade;
	int sum;
	double average;
	char letter;
};

///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////

void readStudentData(studentRecord n[a_row], studentRecord g[a_row][a_col])
{
	inputname.open("name.txt");
	inputscore.open("score.txt");

	inputname.open("name.txt");
	if (!inputname) perror("File not found ");
	else
		cout << "File successfully opened" << endl;

	for (int r = 0; r < a_row; r++)
	{
		getline(inputname, (n[r].name));
		for (int i = 0; i < a_col; i++)
		{
			inputscore >> g[r][i].grade;
		}

	}
}

///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////

void printStudentData1(studentRecord n[a_row], studentRecord g[a_row][a_col])
{
	for (int r = 0; r < a_row; r++)
	{
		cout << n[r].name << "\t";
		for (int i = 0; i < a_col; i++)
		{
			cout << g[r][i].grade << " " << "\t";
		}
		cout << endl;
	}
}

///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////

void sumOfGrade(studentRecord g[a_row][a_col], studentRecord s[a_row])
{
	for (int r = 0; r < a_row; r++)
	{
		for (int i = 0; i < a_col; i++)
		{
			s[r].sum = s[r].sum + g[r][i].grade;
		}
	}
}

///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////

void averageGrade(studentRecord s[a_row], studentRecord a[a_row])
{
	for (int i = 0; i < a_row; i++)
	{
		a[i].average = s[i].sum / (static_cast <double> (a_col));
	}
}
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////

void letterGrade(studentRecord a[a_row], studentRecord l[a_row])
{
	for (int i = 0; i < a_row; i++)
	{
		if (a[i].average >= 90)
		{
			l[i].letter = 'A';
		}
		else if (a[i].average >= 80)
		{
			l[i].letter = 'B';
		}
		else if (a[i].average >= 70)
		{
			l[i].letter = 'C';
		}
		else if (a[i].average >= 60)
		{
			l[i].letter = 'D';
		}
		else
		{
			l[i].letter = 'F';
		}
	}
}

///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////

void printStudentData2(studentRecord n[a_row], studentRecord g[a_row][a_col], studentRecord s[a_row], studentRecord a[a_row], studentRecord l[a_row])
{
	for (int r = 0; r < a_row; r++)
	{
		for (int i = 0; i < a_col; a++)
		{
			cout << n[r].name << "\t";
			cout << "Total: " << s[r].sum << endl;
			cout << "Average: " << a[r].average << endl;
			cout << "Grade: " << l[r].letter << endl;
			cout << g[r][i].grade << endl;
		}
	}
}

///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////

void main()
{
	studentRecord name[a_row];
	studentRecord grade[a_row][a_col];
	studentRecord sum[a_row];
	studentRecord average[a_row];
	studentRecord letter[a_row];

	readStudentData(name, grade);
	printStudentData1(name, grade);
	sumOfGrade(grade, sum);
	averageGrade(sum, average);
	letterGrade(average, letter);
	printStudentData2(name, grade, sum, average, letter);

	inputname.close();
	inputscore.close();
	system("pause");
}

[AbstractionAnon]

Before you convert this to a class, there are some problems you need to cleanup.

Lines 26,29: You open inputname twice.

Lines 138-142: Your studentRecord struct is an aggregate of these fields. You don't want to define a studentRecord for each element.

  studentRecord rec[a_row];  // Define an array of structures 

But is it better to use constructor to doing that

No. You can't return an error from a constructor. It's better to have a separate functions to read / write instances of your class.

[silver11235]

Oh sorry, what I meant was using constructor to write I/O to read and store data into private member ? is it okay to doing that ?

[silver11235]

Also this is how far I have done with I/O with class, somehow it's always give me this error

http://i.imgur.com/c2LzgCz.png

#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
#include <fstream>
using namespace std;

#define a_row 10
#define a_col 6

ifstream inputname, inputscore;

class studentRecord
{
private:
	string name[a_row];
	int grade[a_col];
	int sum;
	double average;
	char letter;
public:
	studentRecord();
	/*void readStudentData(string name, int grade);
	void printStudentData(string name, int grade);
	int sumOfGrade(int grade, int sum);
	double averageGrade(int sum, double average);
	void letterGrade(double average, char letter);
	void printStudentData2(string name, int grade, int sum, double average, char letter);*/
};

studentRecord::studentRecord()
{
	inputname.open("name.txt");
	inputscore.open("grade.txt");

	for (int r = 0; r < a_row; r++)
	{
		inputname >> name[a_row];
		for (int i = 0; i < a_col; i++)
		{
			inputscore >> grade[a_col];
		}
	}
	
}

//int studentRecord::sumOfGrade(int grade, int sum)
//{
//
//}

void main()
{
	studentRecord student;
	system("pause");
}

[AbstractionAnon]

You're still missing a couple of points.

1) A student record object should represent ONE and only one student. name should not be an array. You want to represent multiple students by having an array (or preferably a vector) of studentRecords as I suggested in my previous post.

2) As I also suggested in my previous post, it's not a good idea to open and read a file in a constructor. There are two reasons for this.
a) A studentRecord constructor initializes ONE studentRecord object. You can't read an entire file into an object that represents only one student.
b) Lines 33-34: What happens if either file fails to open? You continue as if nothing has gone wrong.

Line 38,41: These are out of bound references.

Line 52: main must return type int.

#include <iostream>
#include <fstream>
#include <string>
#include <iomanip>
#include <fstream>
using namespace std;

const int MAX_STUDENTS = 10;    // Use meaningful names
const int MAX_GRADES = 6;


class studentRecord
{
private:
	string name;
	int grade[MAX_GRADES];
	int sum;
	double average;
	char letter;
public:
	studentRecord();
	bool Read (istream & inputname, istream & inputscore);
};

//  Constructor
studentRecord::studentRecord ()
{}

bool studentRecord::Read (istream & inputname, istream & inputscore)
{   if (! (inputname >> name))
        return false;  //  failed to read a record
    sum = 0;        
    for (int i = 0; i < MAX_GRADES; i++)
    {   inputscore >> grade[i];    // Could use some error handling here if the read fails
        sum += grade[i];
    }        
    return true;
}

int main()
{   ifstream inputname, inputscore;
    studentRecord student[MAX_STUDENTS];
    int i = 0;
    
   	inputname.open("name.txt");
	inputscore.open("grade.txt");   
	if (inputname.fail() || inputscore.fail())
    {   cout << "Unable to open input file" << endl;
        return 1;
    }	
    while (i < MAX_STUDENTS && student[i].Read (inputname, inputscore))        
         i++;
  system("pause");
  return 0;
}