// Zeinalipour-Yazti Demetrios
// csyiazti
// cs10xx -  Lab Sec#25-#29
// lab8
/* This program defines :
 * a) A function that will randomly generate two operands ranging between 1-1000. 
 *    This function modifes the operands through reference
 * b) A function that takes as parameters, the two operands and will output the
 *    question nicely to the screen. Each question should line up with future 
 *    outputted questions at the addition operator and the equal sign.
 * c) A function that will take as a parameter an integer representing some number
 *    of questions and generate that many test questions. 
 * Then the program will allow the user to specify some number of questions and
 * then will show that many addition questions nicely on the screen.
 */

#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;


/* This function assigns a random number in range (from,to) to the 
 * parameters passed by reference
 * @return : void
 */
void assignRand(int &start, int &end, int from, int to)
{
    /* e.g (2,4) ==> range=3 [3 numbers] */
	int range = to-from+1;	
	
	// produce twice a random number from <= random <= to
	start = (rand() % range) + from;  
	end   = (rand() % range) + from;  
}


/* This function prints 1 equation.
 * @return : void
 */
void printEquation(int start, int end)
{
    cout << setw(5) << setiosflags(ios::left) << start 
		 << " + " << setw(5) << setiosflags(ios::left) 
		 << end << " = " << endl;
}


/* This function prints N equations
 * @return : void
 */
void print_N_Equationa(int N)
{
	int start;  // the first random
	int end;	// the second random
	void assignRand(int &start, int &end, int from, int to);
	void printEquation(int start, int end);
	
	// iterate N times 
	for (int i=0; i<N; i++)
	{
		assignRand(start,end, 1, 1000);
		printEquation(start,end);
	}
    
}

/* Get value from user along with error checking etc
 * @return : the INT value given by the user
 */
int getUserTimes()
{
	int val;
	cout << "Please enter the number of equations to create: ";
	cin >> val;

	while (cin.fail())
	{
		cout << "#ERROR - Only integer  values are allowed!\n";
		cin.clear();
		cin.ignore(80, '\n');
		cout << "Please enter the number of equations to create: ";
		cin >> val;
	}
	return val;
}


/* This function asks the user to select the char "y" or "n" 
 * @return : y for yes
 *           n for no
 */
char doAgain()
{    /* defining local scope variables*/
     char value;

     cout << "\nDo you want to run the program again (y/n) ?:  ";
     cin >> value;
     while (cin.fail() || !(value=='y' || value=='n'))
	 {
		 cout << "#Error - only (y/n) are accepted!\n";
		 cin.clear();
		 cin.ignore(80, '\n');
		 cout << "Do you want to run the program again (y/n) ? :  ";
		 cin >> value;
	 }
	 cout << endl;
     return value;
}



void main()
{
	/* define variables */	
	int x;			/* the equations to create per round */ 

	/* declare functions & procedures*/
	int getUserTimes(); /* get a correct int value from user	*/	
	char doAgain(); /* returns 'y' or 'n' to the question whether to continue  */
	
	
	cout << "Random Equation Generator by Demetris Zeinalipour - Lab 9 \n\n";
	// run the program as many times as the user wants		
	do 
	{	
		// get the input from user in a function-fashion way 		
		x = getUserTimes();  // ask the user how many equations to create
		
		/* print x Equations */	
		print_N_Equationa(x);		

	} while (doAgain()=='y');

}