lesson10part2.txt

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

using namespace std;

//our one global constant
const int MAX_COLUMNS = 5;

//our four function prototypes
int readFile(double[][MAX_COLUMNS], int, string );
double average(double[][MAX_COLUMNS], int n);
double columnAverage(double[][MAX_COLUMNS], int, int);
double smallestInRow(double[][MAX_COLUMNS], int);

int main()
{
	string inputFileName; //this will hold our file name
	const int MAX_ROWS = 30; //max number of rows
	double grades[MAX_ROWS][MAX_COLUMNS]; //initializes our array
	int rows; //this will hold the output of readFile, the file qualifies

	//these will get a file name from the user
	cout << "Enter input file name\n";
	cin >> inputFileName;

	if (readFile(grades, MAX_ROWS, inputFileName) == -1) //in case file can't open
	{
		cout << "File \"" << inputFileName << "\" could not be opened\n";
		return 0;
	}
	else if (readFile(grades, MAX_ROWS, inputFileName) == 0) //in case the file is empty
	{
		cout << "The input file \"" << inputFileName << "\" did not contain any data\n";
		return 0;
	}
	else //if the file opens and has data
	{
		rows = readFile(grades, MAX_ROWS, inputFileName); //uses readFile to discern the number of rows of data in our file

		//the rest of main is just displaying the results of the various functions
		cout << "Processing " << rows << " rows, and " << MAX_COLUMNS << " columns\n";
		cout << "Average for all values is " << fixed << setprecision(2) << average(grades, rows) << "\n";

		for (int i = 0; i < MAX_COLUMNS; ++i)
		{
			cout << "Average for column " << i << " is " << fixed << setprecision(2) << columnAverage(grades, i, rows) << "\n";
		}

		for (int i = 0; i < rows; ++i)
		{
			cout << "Smallest value for row " << i << " is " << fixed << setprecision(2) << smallestInRow(grades, i) << "\n";
		}

		return 0;
	}
}

int readFile(double values[][MAX_COLUMNS], int maxRows, string inputFileName)
{
	ifstream inputFrom;
	inputFrom.open(inputFileName.c_str());
	int dataPointCount = 0; //will act as a counter for how many data points we have
	int rowCount = 0; //will act as a counter for how many rows we read

	if (inputFrom)
	{
		//this for loop was an alternative method I found for doing what the while loop does
		/*for (int i = 0; i < maxRows; ++i)
		{
			for (int j = 0; j < MAX_COLUMNS; ++j)
			{
				if (inputFrom >> values[i][j])
				{
					++dataPointCount;
					rowCount = dataPointCount / MAX_COLUMNS;
				}
			}
		}*/
		int i = 0, j = 0; //these will act as loop control variables
		while (i < maxRows && j < MAX_COLUMNS && inputFrom >> values[i][j]) //reads data from our file into our array
		{
			if (j != 0 && j % (MAX_COLUMNS-1) == 0) //these conditions and block will shift the values array to the next row
			{
				++i;
				j = 0;
			}
			else //shifts the values array to the next column
				++j;
			++dataPointCount; //counts our data points
		}
		
		if (i > maxRows) //if i > maxRows then it can only be greater by 1, so...
			rowCount = i - 1;
		else  //i will end as the number of rows of data
			rowCount = i;
		
		inputFrom.close(); //closes our file if it was opened

		if (dataPointCount < 5) //not enough data
			return 0;
		else
			return rowCount; //everything went well, function returns number of rows of data in the input file
	}
	else
		return -1; //indicates file couldn't be opened
}

double average(double values[][MAX_COLUMNS], int numberRows)
{
	int dataPointCount = 0; 
	double sumOfDataPoints = 0;
	double average;
	for (int i = 0; i < numberRows; ++i) //loops through all elements in the values array, sums them, and counts how many there are
	{
		for (int j = 0; j < MAX_COLUMNS; ++j)
		{
			sumOfDataPoints += values[i][j];
			++dataPointCount;
		}
	}
	average = sumOfDataPoints / dataPointCount; //calculates average
	return average;
}

double columnAverage(double values[][MAX_COLUMNS], int column, int numberRows)
{
	double sumOfColumn = 0;
	double average;
	for (int i = 0; i < numberRows; ++i) //loops through all elements in a column and sums them
	{
		sumOfColumn += values[i][column];
	}
	average = static_cast<double>(sumOfColumn) / numberRows; //calculates average
	return average;
}

double smallestInRow(double values[][MAX_COLUMNS], int row) //modified find-minimum-in-list algorithm
{
	double min = values[row][0];
	for (int i = 1; i < MAX_COLUMNS; ++i)
	{
		if (values[row][i] < min)
			min = values[row][i];
	}
	return min;
}