integer division / modulus controlled looping

[Griff0527]

I am trying to edit my current homework assignment to include a loop that lets the user repeat the computation for new values until the user says they want to end the program. I was given a hint to use integer division and the % operator to implement this function. I have created the program from scratch and researched my book for the last 3 hours (plus online), but cannot figure out how to use integer division and modulus as a loop control. Can someone help explain it to me? Below is the code I have written (it compiles and runs with no errors), and it exits properly if the integer entered is more than 100 or less than zero. Any guidance would be a great help, or a link to C++ documentation describing how to use int division and modulus as a loop control.

Thank you,
Griff0527

#include <iostream>
using namespace std;

void computeCoin(int coinValue, int& number, int& amountLeft);
//Precondition: 0 < coinValue < 100; 0 <= amountLeft < 100.
//Postcondition: number has been set equal to the maximum number
//of coins of demonination coinValue cents that can be obtained
//from amountLeft cents.  amountLeft has been decreased by the
//value of the coings, that is, decreased by number*coinValue.

void quartersOut(int number);
void dimesOut(int number);
void penniesOut(int number);

int main( )
{
	int number = 0, // counter for the coins
		amountLeft; // amount remainig to be disbursed
	
	cout << "Enter the amount of change between 0 and 100\n to determing the proper coinage to be disbursed: ";
	cin >> amountLeft; // input amount to be dispensed

	if ((amountLeft < 100) && (amountLeft > 0))
	{

		cout << amountLeft << " cents can be given as:" << endl << endl; // prepatory output based on input
	
		computeCoin(25, number, amountLeft); // call the function to calculate quarters
		quartersOut(number);

		number = 0; // reset counter to zero
		computeCoin(10, number, amountLeft); // call the function to calculate dimes
		dimesOut(number);

		number = 0; // reset counter to zero
		computeCoin(1, number, amountLeft); // call the function to calculate pennies
		penniesOut(number);
	}

	else
	{
		cout << "I'm sorry, you have entered a number outside the scope of this program" << endl;
	}

	return(0);
}

void computeCoin(int coinValue, int& number, int& amountLeft)
{
	while (amountLeft >= coinValue)
	{
		amountLeft = amountLeft - coinValue;
		number++;
		//cout << "amountLeft = " << amountLeft << endl;
		//cout << "number = " << number << endl;
		//cout << "coinValue = " << coinValue << endl;
		
	}
}

void quartersOut(int number)
{
	cout << number << " quarter(s) "; // output for quarters
}

void dimesOut(int number)
{
	cout << number << " dime(s) and "; // output for dimes
}

void penniesOut(int number)
{
	cout << number << "penny(pennies)" << endl << endl; // output for pennies
}

[NathanOliver]

well if you want the user to be able to keep inputting a number for the change to be computed the you can wrap the whole thing in a while loop

char ch = 'y';
while (ch == 'y' || ch == 'Y')
{
    // lines 17-44 here
    cout << "Enter 'y' to continue 'n' to stop: ";
    cin >> ch;
}

[Griff0527]

Right,
I know how to use a character to control the loop, but for the sake of the assignment, I am trying to understand how to use integer division and modulus to do the same thing as using a character to control the loop. I am going off the suggested "Hint" that our instructor gave us. Thank you though for the tip.
If anyone can assist on the integer division, that would be great. I am tempted to use a char as the control in order to be only one day late instead of two.

well if you want the user to be able to keep inputting a number for the change to be computed the you can wrap the whole thing in a while loop

char ch = 'y';
while (ch == 'y' || ch == 'Y')
{
    // lines 17-44 here
    cout << "Enter 'y' to continue 'n' to stop: ";
    cin >> ch;
}

[NathanOliver]

Was the hint for how to calculate the change or for how to let the user keep entering in more numbers?

[Griff0527]

The exact hint said "Include a loop that lets the user repeat this computation for new input values until the user says he or she wants to end the program. (Hint: Use integer division and the % operator to implement this function.)"

So, I suppose it could be read either way... I, of course, choose to take it the most complex way so that I can learn more. Is loop control via integer division possible without a pre-set limit? ie. for (i < 10000, i/10, i++) or some other nonsense where you would much rather use simple counter addition to control the loop? Perhaps I am over-thinking the issue?

[NathanOliver]

I think the hint might be for the the change function and not for the user input loop. the change function you wrote could be rewritten like this

void computeCoin(int coinValue, int& number, int& amountLeft)
{
    if (amountLeft % coinValue == 0)
    {
        number += amountLeft / coinValue;
        amountLeft = 0;
    }
    else
    {
        number += amountLeft / coinValue;
        amountLeft = amountLeft % coinValue;
    }
}

[Griff0527]

That makes sense. Thanks for the help Nathan. I appreciate you straightening me out a bit.

[invisal]

NathanOliver, don't you think that condition is unnecessary?

[NathanOliver]

Yes it is unnecessary. Didn't really think about it I just wrote what first came to mind. Thanks for pointing that out invisal. It could easily be written this way and it is probably faster.

void computeCoin(int coinValue, int& number, int& amountLeft)
{
    number += amountLeft / coinValue;
    amountLeft = amountLeft % coinValue;

}