//------------------------------------------------------------------
//
// A program that illustrates the use of arrays in 
// the context of the patient record example.
//
// Simon Parsons
// March 6th 2007.
//
//------------------------------------------------------------------

//------------------------------------------------------------------
//
// Link the necessary libraries

#include <iostream>
#include <fstream>

using namespace std;

//------------------------------------------------------------------
//
// Declare variables

int idNumber;
int age;
int disease;
int zipCode;

//------------------------------------------------------------------
//
// A method to print out the patient data

void printRecord()
{
  cout << "Patient ID: \t"  << idNumber << endl;
  cout << "Age: \t\t"       << age      << endl;
  cout << "ZIPcode: \t"     << zipCode  << endl;
  cout << "Suffers from: \t"<< disease  << endl;
  cout << endl;
}

//------------------------------------------------------------------
//
// The main method

int main()
{

    // Initialisation

    const int LENGTH = 7;           // The length of arrays
    int diseases[LENGTH];           // Declare two arrays to hold
    int ages[LENGTH];               // patient data
    int recordCounter;              // Declare counter
    int sumOfAges =0;               // Two variables to hold aggregate
    int numberOfDiseases = 0;       // data

    ifstream infile("patient.dat"); // Open the patient record file

    //--------------------------------------------------------------
    //
    // Read records from the file

    for(recordCounter = 0; recordCounter < LENGTH ; recordCounter++)
    {
        infile >> idNumber;         // Read data in from
        infile >> age;              // file.
        infile >> disease;
        infile >> zipCode;

        // Store disease and age data in arrays

        diseases[recordCounter] = disease;
        ages[recordCounter]     = age;

        printRecord();              // Print data
    }

    infile.close();                 // Close file

    //--------------------------------------------------------------
    //
    // Print out diseases in reverse order

    cout << endl << "Diseases in reverse order" << endl << endl;

    for(recordCounter = LENGTH - 1; recordCounter >= 0;  recordCounter--)
    {
        cout << diseases[recordCounter] << endl;
    }

    //--------------------------------------------------------------
    //
    // Compute average age of patients

    for(recordCounter = 0; recordCounter < LENGTH;  recordCounter++)
    {
      sumOfAges += ages[recordCounter];  // Add each age in turn to
    }                                    // the aggregate age.

    // Set the number of decimal places of the output

    cout.setf(ios::fixed, ios::floatfield);
    cout.precision(1);

    // Calculate the average age and print it

    cout << endl << "Average age is ";
    cout << endl << sumOfAges / (LENGTH * 1.0) << endl;

    //--------------------------------------------------------------
    //
    // Count the number of cases of a given disease.


    // Get disease number from user

    cout << endl << "Enter disease: ";
    cin  >> disease;

    // Count the number of times we see that disease

    for(recordCounter = 0; recordCounter < LENGTH;  recordCounter++)
    {
      if(diseases[recordCounter] == disease)  // If the disease in the 
	{                                     // array matches the one we
	  numberOfDiseases += 1;              // are looking for, increase 
	}                                     // the count.
    }

    // Print out the number of times we found the disease

    cout << endl << "Number of patients with ";
    cout << disease << " is " << numberOfDiseases << endl;

    //--------------------------------------------------------------
    //
    // End.
    
    // Note that we closed the file way back

    return 0;
}