// John Bent's CS 110 Hand-out 4
// Parrallel arrays.
//
// Limitations:	  MINIMAL error checking. 


#include<iostream.h>
#include<fstream.h>

// make the maxsize easily accessible, facilitating easy change
const int MAXSIZE = 100;

// function prototypes
// for a description, see their implementations
void initialize (int&, int&, int&, int&, int&);
int getAve_Method1 (int, int, int);
void getAve_Method2 (int, int, int, int&);
void show (int[], int[], int);


// main() starts here
int main()
{

	// parrellel arrays to hold student data
	int ID[MAXSIZE], Quiz1[MAXSIZE], Quiz2[MAXSIZE], Quiz3[MAXSIZE],
		FinalAve[MAXSIZE];

	// other non-array variables
	int students, i;  // students is number of students in teacher's class
			  // i is for loops
	char answer;	  // does teacher want to enter by hand or batch?


	for (i = 0; i < MAXSIZE; i++)
		initialize (ID[i], Quiz1[i], Quiz2[i], Quiz3[i], FinalAve[i]);

	do {
		cout << "\nHow many students do you have? ";
		cin >> students;
	}
	while (students < 1 || students > 100);

	do {
		cout << "\nWould you like to enter the info by [H]and or "
	     	<< "is it in a [B]atch file? ";

		cin >> answer;
	} while (answer != 'B' && answer != 'b' && answer != 'H' && answer != 'h');

	if (answer == 'B' || answer == 'b') {
		char filename[100];
		
	 	cout << "\nPlease enter the file name: ";
                cin >> filename;
                ifstream infile (filename, ios::in);

		if (!infile) {  // file not found
			cout << "\nI'm sorry.  I could not find "
			     << filename << ".\n";
			return 1; // kick out the user for entering a bad filename
		}  // end if

	 	// file is there, get the data
		for (i = 0; i < students && !infile.eof(); i++)
                        infile >> ID[i] >> Quiz1[i] >> Quiz2[i] >> Quiz3[i];

		infile.close(); // clean up after yourself
	} // end if
	else {  // user wants to enter by hand

		for (i = 0; i < students; i++)
		{
		cout << "Enter ID followed by three quiz scores: ";
		cin >> ID[i] >> Quiz1[i] >> Quiz2[i] >> Quiz3[i];
		}

	}  // end else, arrays have been filled 
	

	// do the averages - two ways
	for (i = 0; i < students; i++)
		FinalAve[i] = getAve_Method1(Quiz1[i], Quiz2[i], Quiz3[i]);

	// OR this way
	for (i = 0; i < students; i++)
		getAve_Method2(Quiz1[i], Quiz2[i], Quiz3[i], FinalAve[i]);

	// show them
	show (ID, FinalAve, students);

return 0;
}

// this function is passed the addresses of five integers and set their
// values to zero
//
void initialize (int &id, int &Q1, int &Q2, int &Q3, int &Ave)
{
	id = Q1 = Q2 = Q3 = Ave = 0;
}


// this function makes copies of three integer values, and returns 
// their average
//
int getAve_Method1 (int One, int Two, int Three)
{
	return ( (One + Two + Three) / 3 );
}


// this function is identical to the previous except that it does
// not need to return the average because it is passed the address
// where the average needs to go
void getAve_Method2 (int One, int Two, int Three, int &ave)
{
	ave = (One + Two + Three) / 3;
}


// this function takes the addresses of two arrays and makes a copy
// of one integer value which is the working size of the arrays
// it then traverses the arrays, printing the values
//
void show (int identityNo[], int ave[], int number_students)
{
	for (int i = 0; i < number_students; i++)
		cout << identityNo[i] << " " << ave[i] << endl;
}