// Lab 7 Lecture

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

#include <iostream>
using namespace std;

int main()
{


// ----------------------------- While Loops ----------------------------------

	// Here is an example of a simple WHILE Loop
	// while ( <conditional statement> )
	// {
	//		// statements
	// }
	
	// Like a FOR loop the while loop will only execute if the conditional
	// statement is true, and will loop back up and continue to execute 
	// over and over until the condition is false.
	
	// notice that the following is impossible to tell how many times it will
	// execute. It will depend on what the user inputs.

	char ans = 'y';
	cout << "Entering WHILE Loop (enter 'n' to quit loop)" << endl;

	while (ans != 'n')
	{
		cout << "Bears, beets, Battlestar Galactica." << endl;
		cin >> ans;
	}

	
// ----------------------------- Do-While Loops -------------------------------

	// Here is an example of a simple DO-WHILE Loop
	// do{
	//		// code
	// } WHILE ( <conditional statement> );


	char ans2 = 'y';
	cout << "Entering DO-WHILE Loop (enter 'n' to quit loop)" << endl;

	do{
		cout << "Bears beets Battlestar Galactica." << endl;
		cin >> ans2;
	}while (ans2 != 'n');


// ------------------------- While Vs. Do-While Loops -------------------------

	// There is a very subtle difference between a WHILE and a
	// DO-WHILE loop. A WHILE loop tests it's condition before
	// entering the loop, whereas a DO-WHILE loop will test after the
	// code inside the loop has executed. This means that a DO-WHILE
	// loop will always run its code at least once, whereas a WHILE loop
	// may never run it's code. This can be demonstrated via the following.

	cout << "WHILE loop Vs. DO-WHILE loop" << endl;

	//while
	while(false){
		cout << "WHILE LOOP WIN" << endl;
	}

	//do-while
	do{
		cout << "DO-WHILE LOOP WIN" << endl;
	}while(false);


// ----------------------------- Infinite Loops -------------------------------

	// one thing you must always be careful when dealing with loops is the possibility
	// of an infinite loop. Why is this an infinite loop? (uncomment before you run)

//	int choice, i;
//	cout << endl << "Enter a positive number." << endl;
//	cin >> choice;
//
//	i = 0;
//	while (i < choice){
//		cout << "In infinite loop" << endl;
//	}


// ------------------------------ Nested Loops --------------------------------

	// While and do-while loops can be nested. How many times will the 'cout' 
	// execute? This is also how to implement a while loop to iterate a specific
	// number of times. 

	const int SIZE2 = 3;
	int k;
	int j;
	int count_1 = 0;
	cout << "\nEntering WHILE Loop 3" << endl;


	k = 0;
	while (k < SIZE2){
		j = 0;
		while (j < SIZE2){
			count_1++;
			cout << "k : " << k << " j : " << j
				 << " count : " << count_1 << endl;
			j++;
		}
		k++;
	}

	cout << endl;
	
	// Would a FOR loop be better suited for this task?

// ------------------------- Do-While Loop Example ----------------------------

	// This program finds the factorial of any number below 20.
	// The program will loop until it is told to terminate.

	int selection, g;
	long long int total; // can hold very large positive integers
	char menu;
	do{
		cout << "Welcome to my factorial calculator!" << endl;
		cout << "Please enter a positive number to find it's factorial!" << endl;
		cin >> selection;

		if (!selection) { // if selection is equal to 0 return true (!0 = 1)
			cout << "0! = 1" << endl;

		} else if (selection > 20) {
			cout << "The number entered is too large." << endl;

		} else if(selection > 0) {
			g = 2;
			total = 1;
			while (g <= selection){
				total *= g;
				g++;
			}
			cout << selection << "! = " << total << endl;

		} else {
			cout << selection << "! = undefined" << endl;
		}

		cout << "Would you like to calculate another number? ('y' or 'n')" << endl;
		cin >> menu;

	}while(menu != 'n');

	cout << "PROGRAM TERMINATED" << endl;

	return 0;
}