//-------------------------------------------------------------
// Filename:  formatted2.cpp
// Purpose:   Demonstrate filling parallel arrays from a file 
// Author:    Susan Gauch
//-------------------------------------------------------------
#include <fstream>
#include <iostream>
using namespace std;

const int MAXSTUDENTS = 100;

//-------------------------------------------------------------
// Name:     FillArrays
// Purpose:  Fill three arrays from a file that is already open
//           Also set NumStudents to the number of records read
//-------------------------------------------------------------
void FillArrays(ifstream & Din, int IDs[], float GPAs[], string Names[],
		int &NumStudents)
{
   NumStudents = 0;
   while ((NumStudents < MAXSTUDENTS) &&
	  (Din >> IDs[NumStudents] >> GPAs[NumStudents] >>
	   Names[NumStudents]))
      NumStudents++;
}

//-------------------------------------------------------------
// Name:     PrintStudent
// Purpose:  Prints the information for one student 
//-------------------------------------------------------------
void PrintStudent(const int IDs[], const float GPAs[],
		  const string Names[], const int StudentNum)
{
   cout << IDs[StudentNum] << " "
        << GPAs[StudentNum] << " " 
        << Names[StudentNum] << endl;
}

//-------------------------------------------------------------
// Name:     PrintArrays
// Purpose:  Print three arrays to the screen
//-------------------------------------------------------------
void PrintArrays(const int IDs[], const float GPAs[],
		 const string Names[], const int NumStudents)
{
   for (int s = 0; s < NumStudents; s++)
      PrintStudent(IDs, GPAs, Names, s);
}

//-------------------------------------------------------------
// Name:     CalcAverage
// Purpose:  Return the average GPA for the students
//-------------------------------------------------------------
float CalcAverage(const float GPAs[], const int NumStudents)
{
   // Add all the GPAs together
   float Sum = 0;
   for (int s = 0; s < NumStudents; s++)
      Sum += GPAs[s];
   return Sum / NumStudents;
}

//-------------------------------------------------------------
// Name:     FindTopStudent
// Purpose:  Return the location of the top student
//-------------------------------------------------------------
int FindTopStudent(const float GPAs[], const int NumStudents)
{
   // Search array for highest GPA
   int TopLoc = 0;
   for (int s = 1; s < NumStudents; s++)
      if (GPAs[s] > GPAs[TopLoc])
	 TopLoc = s;
   return TopLoc;
}

//-------------------------------------------------------------
// Name:     main
// Purpose:  Read student data and print information
//-------------------------------------------------------------
int main()
{
   ifstream Din;
   string Filename;
   int IDs[MAXSTUDENTS];
   float GPAs[MAXSTUDENTS];
   string Names[MAXSTUDENTS];
   int NumStudents = 0;
   float Average;
   int TopLoc;

   // Get the filename from the user
   cout << "Enter the data file's name: ";
   cin >> Filename;

   // Open the student data  file 
   Din.open(Filename.c_str());
   if (Din.fail())
      cerr << "Error, " << Filename << " did not exist.\n";
   else
   {
      // Read all student data
      FillArrays(Din, IDs, GPAs, Names, NumStudents);
      Din.close();

      // Print all student data 
      cout << "\nThe file contained: \n";
      PrintArrays(IDs, GPAs, Names, NumStudents);

      // Calculate the class average
      Average = CalcAverage(GPAs, NumStudents);
      cout << "\nThe class average is: " << Average << endl;

      // Find the top student
      TopLoc = FindTopStudent(GPAs, NumStudents);
      cout << "The top student is: ";
      PrintStudent(IDs, GPAs, Names, TopLoc);
   }
   return 0;
}