// Zeinalipour-Yazti Demetrios
// csyiazti
// cs10xx -
// Lab Sec#24
// lab6
	/*	Rectangle Area - WITH PROCEDURES & FUNCTIONS
	 *	This program allows the user to calculate the area of a rectangle many times.	   
	 *	A) Input: length, width, continue/quit
	 *	B) Restrictions: inputs must be positive
	 *	C) Output: area
	 *	D) Formula: area = length * width
     *
	 */
#include <iostream.h>


/* This function asks the user to input the value: valuename[] repetively until a
 * correct (>0) value is given. It then returns this value
 */
int getValue(char valuename[])
{    /* defining local scope variables*/
     int value;

     /*  Getting the value */
     while (true) //start while1a
     {
    	  cout << "\nPlease type in the (positive) \"" << valuename << "\" of the square: ";
    	  cin >> value;
    	  if (value>0)
    		{ break; }
    	  else
    	  	{ cout << "Error# - The value you entered is not a positive integer: " << endl; }
     }	//end while1a
     return value;
}



/* This function calculates the area of the rectangle and returns that value
 */
int calculateArea(int length, int width)
{
     return length*width;
}


/* This procedure simply outputs the area of the rectabgle along with the values of the 2 axis 
 */
void printOutput(int length, int width, int area)
{
	cout << "The area of the square ("
	     << length << "x" << width << ") = "
	     << area << endl << endl << endl;
}



/* This function asks the user if he wants to run the program again. 
 * The function insists on asking until a valid answer is given ('y' OR 'n'). It thens
 * returns an aswer (true OR false) to this question.
 */
bool doCalculationAgain()
{	
	char quitquestion;			/* Field to store users answer on quit question */
	bool correctinput = false;  /* Has the user entered a correct input         */
	bool quit = false;			/* The question to be answered in this module   */


    /*  Asking if the user want to execute again */
	while (!correctinput)
	{
		  cout << "Do you want to do the calculation again? (y/n): ";
		  cin >> quitquestion;
		  switch (quitquestion)
		  { case 'y' : correctinput = true;
					   break;
			case 'n' : quit = true;
					   correctinput = true;
					   break;
			default: cout << "Error# - Please use \"y\" for yes OR \"n\" for no!\n\n";
		  }
	}//end while1b
 	
	return quit; 

}


void main()
{
	/* define variables */
	int length;							 /* The length of the square                     */
	int width;		 					 /* The width  of the square                     */
	int area;							 /* The area of the square                       */
	bool quit  = false;					 /* Should the program stop executing            */
	
	/* define functions & procedures*/
	int getValue(char valuename[]);		/* returns the "correct' value given by the user */
	int calculateArea(int length, int width); /* returns the area of the given rectangle */
	void printOutput(int length, int width, int area);					 /* outputs area */
	bool doCalculationAgain();	/* returns true if user if he wants to run program again */
	
	/* */
	while (!quit)  //start while1
	{
		  /* get Values from user  */	
		  length = getValue("Length");
          width  = getValue("Width");

		  /* Calculating the square of the given values */
		  area = calculateArea(length,width);

		  /* Printing out the result */
		  printOutput(length, width, area);
		  
		  /* Ask the user if he */
		  quit = doCalculationAgain();

	} // end while1
}