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

#define NUMTESTS 3
#define INFILE "studentTests.dat"
#define OUTFILE "studentAvg.out"
#define INFLAG 1
#define OUTFLAG 0

using namespace std;

/**************************/
/*  Function Prototypes   */
/**************************/
// open inputfile
void openFile(string filename, fstream &fs, int flags);
// Get the student's SSN and test scores
void getStuInfo(fstream &ins, string &ssn, float &test1, 
		float &test2, float &test3);
// Calculate the average of the three test scores
float calcAvg(float score1, float score2, float score3);
// Print student's SSN and test average
void printStuInfo(fstream &outs, string ssn, float testAvg);

int main()
{
  float test1, test2, test3;
  float avg;
  string ssn;
  fstream ins;  // input file stream declaraction
  fstream outs; // output file stream declaraction


  openFile(INFILE, ins, INFLAG);
  openFile(OUTFILE, outs, OUTFLAG);

  // read first line; handles empty file
  getStuInfo(ins, ssn, test1, test2, test3);

  // while not EOF, read data, calc avg, output avg for a student
  while (!ins.eof()) {
    avg = calcAvg(test1, test2, test3);
    printStuInfo(outs, ssn, avg);
    getStuInfo(ins, ssn, test1, test2, test3);
  }  // end while !EOF

  // close files
  ins.close();
  outs.close();

  return 0;
}  // end main



void openFile(string filename, fstream &fs, int flags)
{
  if (flags == INFLAG)
    fs.open(filename.c_str(), ios::in);
  else
    fs.open(filename.c_str(), ios::out);
  if (fs.fail()) {
    cout << "Error opening input file " << filename << endl;
    exit(1);
  }  // end if fail
  return;
}


void getStuInfo(fstream &ins, string &ssn, float &test1, 
		float &test2, float &test3)
{
  ins >> ssn;
  ins >> test1;
  ins >> test2;
  ins >> test3;

  return;
}  // end function getStuInfo


float calcAvg(float score1, float score2, float score3)
{
  float sum;
  float ave;

  sum = score1 + score2 + score3;
  ave = sum / NUMTESTS;

  return ave;
}  // end function calcAvg


void printStuInfo(fstream &outs, string ssn, float testAvg)
{
  outs << fixed << showpoint << setprecision(2);
  outs << ssn << " " << testAvg << endl;

  return;
}  // end function printStuInfo