// Lab 8 Lecture

// comment the examples and run individually or several at once
// by commenting out the indicated sections of code.
// (Eclipse: ctrl+/ to comment and uncomment)
// (Code Blocks: ctrl+shift+C to comment and ctrl+shift+x to uncomment)

#include <iostream>
#include <fstream>

using namespace std;

int main()
{


// ------------------------------- Arrays -------------------------------------

	// Variables thus far have only been able to store a single value
	// at a time. However arrays allow you to store multiple values of
	// the same data type.
	//
	// Declaring an empty array of integers with 10 elements:
	//
	//  int array_name [10];
	//
	// ** Note - your array will be filled with garbage until initialized,
	//  just like a regular variable. **


	// Like a regular variable we can declare and initialize
	// an array at the same time. The syntax is a little different
	// because we will be assigning multiple values to it.

	int array_name[10] = {10, 20, 30, 40, 50, 60, 70, 80, 90, 100};

	// This is how our array would look in memory:
	// ____________________________________________________
	// |_10_|_20_|_30_|_40_|_50_|_60_|_70_|_80_|_90_|_100_|  << array elements
	//    0    1    2    3    4    5    6    7    8    9     << index of the element

	// ** Note - the index starts at 0 and not 1. **

	// Once declared, you can access/assign an element individually using the index.
	// here are a few examples:

	array_name[0] = 5;

	cout << array_name[0] << endl;

	array_name[0] = array_name[1] + array_name[2];

	cout << array_name[0] << endl;


// --------------- Iterating Through an Array Using a Loop --------------------
	
	// Loops are an array's best friend and are necessary to traverse them.

	// Here we allow the user to fill an array using a FOR loop

	char array[5];

	cout << endl << "Enter 5 characters" << endl;
	for(int i = 0; i < 5; i++){
		cin >> array[i];
	}

	// Now we print the array back to the screen using another FOR loop

	for(int i = 0; i < 5; i++){
		cout << array[i] << " ";
	}

	cout << endl;


// -------------------- Going Out of Bounds of an Array -----------------------

	// Watch out. It is easy to crash your program with a segmentation fault
	// by attempting to access data outside of your array, or even
	// worse it may allow you to access a memory location not allocated to
	// your array.

	// What error do you get when you run the following code?

	double array_2 [10];

	cout << "Testing Segmentation fault. Creating an array with 10 elements." << endl;

	// notice that this will likely run even though it is outside of your array
	array_2[10] = 100;
	cout << "array element 11 " << array_2[10] << endl;

	// This will almost certainly cause an access violation
	array_2[1000000] = 100;
	cout << "array element 1000001 " << array_2[1000000] << endl;


// ------------------ Understanding the Index of an Array ---------------------

	// The index of an array is simply an integer. Therefore we can save the 
	// index in a variable so we can reference or modify that element later.
	
	// for example we have an array of strings containing the months:

	const string MONTHS[] = { "January", "February", "March", "April", "May", "June",
                                "July", "August", "September", "October", "November",
                                "December"};

	// If the user indicated that their birthday was in June, instead of saving
	// the string "June" we can instead save the index to June which is 5.

	int birthdayIndex = 5;

	// now when we want to print out their birthday month, we can use the following:

	cout << "My birthday is in " << MONTHS[birthdayIndex] << endl;

	// Notice how the index is the variable "birthdayIndex".


// ------------------ Array Example 1 - Searching an Array --------------------

	// Here is a simple algorithm that searches an array for the number 10.

	int array_4[5] = {4, 9, 10, 32, 44};  // array that will be searched

	int searchValue = 10; // the value we are looking for

	int foundIndex = -1;  // the index to where it was found. -1 signals "not found".

	// search array for value
	for(int i = 0; i < 5; i++)
	{
		// if the number we are looking for is found we assign the index
		// to that element into "foundIndex" so that we can do stuff to it
		// later.

		if(searchValue == array_4[i])
		{
			foundIndex = i;
		}
	}

	// print result of search
	if (foundIndex != -1)
	{
		cout << "Found value at index " << foundIndex << endl;
	}
	else
	{
		cout << "Item not found" << endl;
	}


// ---------------- Array Example 2 - File I/O Fixed Size ---------------------

	// here we fill an array using input from a file and send
	// it to an output file.

	// *IMPORTANT*
	// Note that we use ARRAY_SIZE constant to specify
	// the size of our array. This is so that if we decide
	// to change the size of our array, we only have to change
	// that variable and not multiple places. Always try
	// to avoid hard coding literals into your program as it
	// makes your code more difficult to read and maintain.

	const int ARRAY_SIZE = 5;

	int array_5 [ARRAY_SIZE];

	ifstream fin;
	fin.open("input.txt");

	if(!fin){
		cout << "Error - file not found" << endl;
		return 1;
	}


	// Pull ARRAY_SIZE number of data entries into your
	// array. Note that if there are fewer entries in your
	// input file this code will not work properly.

	for (int i = 0; i < ARRAY_SIZE; i++){
		fin >> array_5[i];
	}

	fin.close();

	cout << "Your data has been written to output file - output.txt\n";

	// Send our data to an output file

	ofstream fout;
	fout.open("output.txt");

	for(int j = 0; j < ARRAY_SIZE; j++){
		fout << array_5[j] << " ";
	}

	fout.close();

// --------------- Array Example 2 - File I/O Uncertain Size ------------------


	// This also pulls data from a file into an array, but this time we are
	// uncertain of how many elements are inside the file. Therefore, we use
	// a variable 'count' to keep track of how many items we pulled in.

	const int ARRAY_SIZE_2 = 100;
	int array_3 [ARRAY_SIZE_2];
	int count;

	ifstream fin2;
	fin2.open("input.txt");

	if(!fin2){
		cout << "Error - file not found" << endl;
		return 1;
	}

	count = 0;

	// while the array is not full and the file is not empty,
	// pull data from file and put it into the next array element.
	while(count < ARRAY_SIZE_2 && fin >> array_3[count]){
		count++;
	}

	fin2.close();

	// print array to screen
	for(int k = 0; k < count; k++){
		cout << array_3[k] << " ";
	}
	cout << endl;

	// Now lets send our data to an output file
	ofstream fout2;
	fout2.open("output.txt");

	for(int j = 0; j < count; j++){
		fout2 << array_3[j] << " ";
	}

	fout.close();


	return 0;
}