// This program performs simple statistical analysis 
// of a set of test scores with range 0...100.
// Created by Sebastian Gosztyla

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

const int MAX_ARRAY = 400;

// Function prototypes
void getData(ifstream& inFile, int inValues[], int& size);
void openCheck(ifstream& fileIn);
double getAverage(int inValues[], int dataSize);
double stdDeviation(int inValues[], int dataSize, double average);
void minMax(int inValues[], int numVals, int&min, int&max);
void quartile(int inValues[], int numVals, int min, 
			  int max, double average, double deviation);

int main()
{	
      
	// Declare local variables for main
	ifstream fileIn;                
	// Array for data storage
	int testScores[MAX_ARRAY];     
    // Actual number of values in array
	// (1 more than largest index)
	int numElems, min, max; 
    double average, deviation;                            

    // Open file
	fileIn.open("pgm5data.txt"); 
    
    // Test for file existence
	openCheck(fileIn);
	
	// Read file and count values in array
    getData(fileIn,testScores,numElems);

	// Test for non-empty data file   
    if (numElems == 0)
       cout << "ERROR:  No data processed" << endl << endl;
	
	//Mininum and Maximum
	minMax(testScores,numElems,min,max);

	//Average
	average = getAverage(testScores,numElems);

	//Standard Deviation
	deviation = stdDeviation(testScores,numElems,average);

	//Quartile
	quartile(testScores,numElems,min,max,average,deviation);
	
	// Close file
    fileIn.close();  
	   
   // Terminate program
   return 0; 
}

//-----------------------------------------------------------
// This function reads integers from a file and stores the values in
// an array.  It returns the loaded array and the number of elements 
// in the array
void getData(ifstream& inFile, int inValues[], int& numVals)
{
    int i = 0;
    inFile >> inValues[i];                
    // Test for end of file and array
	while (!inFile.eof() && i < MAX_ARRAY)     
    {
       i++;        
       inFile >> inValues[i];
    }            
    numVals = i;
}

//-----------------------------------------------------------
// This function checks to see if the file exists
void openCheck(ifstream& fileIn)
{

	 if (fileIn.fail() )         
    {
      cout <<  "Problem opening file";
      exit(-1);
    }
}


//-----------------------------------------------------------
// This function receives an array of integers, calculates the average
// of the array values, and returns it.
double getAverage(int inValues[], int dataSize)
{
    double sum = 0.0;
    
    for (int i = 0; i < dataSize; i++)
       sum = sum + inValues[i];    
       
    return sum / dataSize;
}

//-----------------------------------------------------------
// This function reads integers from an array and determines
// the minimum and maximum value in that array.
void minMax(int inValues[], int numElems, int&min, int&max)
{
    max = inValues[0];
	min = inValues[0];
	int i = 0;
	for (int i = 0; i < numElems; i++)
	{ if (max < inValues[i]) 
		max = inValues[i]; 
	 if (min > inValues[i]) 
		min = inValues[i]; 
	}
}

//-----------------------------------------------------------
// This function receives an array of integers, calculates 
// the standard deviation and returns it.
double stdDeviation(int inValues[], int numElems, double average)
{
    double sum = 0.0;
    
    for (int i = 0; i < numElems; i++)
       sum = sum + pow((inValues[i] - average),2);    
       
    return sqrt((1.0/numElems) * sum);
}

//-----------------------------------------------------------
// This function reads in an array of test scores and 
// determines which quartile they fall into. 
void quartile(int inValues[], int numElems, int min, 
			  int max, double average, double deviation)
{
	int quartile1=0, quartile2=0, quartile3=0, quartile4=0;
	for (int i = 0; i < numElems; i++)
	{ if (inValues[i]< 25) 
		quartile4++; 
	else if (inValues[i] < 50)
		quartile3++;
	else if (inValues[i] < 75)
		quartile2++;
	else
		quartile1++;
	}
	
	cout 
		 << "SUMMARY" << endl << endl
		 << setprecision(2) << fixed
		 << "Number of Elements: " << numElems << endl
		 << "Standard Deviation: " << deviation << endl
		 << "Max: " << max << endl
		 << "Min: " << min << endl
		 << "Average: " << average << endl
		 << "Quartile 1: " << quartile1 << endl
		 << "Quartile 2: " << quartile2 << endl
		 << "Quartile 3: " << quartile3 << endl
		 << "Quartile 4: " << quartile4 << endl;
}