Code Sample #6

//               Course:  CS2400-60 Computer Science 2
//                 Name:  Abdalkarim, Marina
//           Assignment:  Programming Assignment P5.2
//               Remark:  The program tests all functions.
#include <iostream>
#include <string>
using namespace std;
struct rational
{
	int num;	// numerator
	int den;	// denominator; b ≠ 0
};
int fillArray(rational r[], int size);
// Precondition: address & physical size of the rational array declared in the calling function must be passed to the function
// Postcondition: returns the actual # of rational numbers entered by user which must be less than or equal to size
void displayArray(rational r[], int n);
// Postcondition: display n rational numbers
void sortRationalNumbers(rational r[], int n);
// Precondition: address of the rational array declared in the calling function and the # of elements to be sorted must be passed to the function
// Postcondition: n rational number is the array are sorted in ascending order
int findSmallestRationalNumber(rational r[], int first, int n);
// Precondition: accepts address, subscript value of the first element of the unsorted sub-list, and the # of array elements n 
// Postcondition: returns subscript value of the smallest rational number in the unsorted sub-list of the array
void swap(rational &r1, rational &r2);
// Postcondition: contents of memory locations referenced by r1 and r2 are swapped
int GCD(const rational &r);
// You must use the Euclidean algorithm. https://en.wikipedia.org/wiki/Euclidean_algorithm
// Postcondition: returns the "greatest common divisor" between r.a and r.b
int main()
{
	const int SIZE = 6;
	rational s[SIZE];
	int fill, small = 0;
	findSmallestRationalNumber(s, small, SIZE);
	fill = fillArray(s, SIZE);
	cout << endl << endl;
	cout << "Before sort, array contains: " << endl;
	displayArray(s, SIZE);
	cout << endl;
	sortRationalNumbers(s, SIZE);
	cout << endl;
	cout << "...Sorting..." << endl << endl;
	displayArray(s, SIZE);
	cout << endl;
	return 0;
}
int fillArray(rational r[], int size)
{
	char ask = 'y';
	int more = 1;
	int i = 0;
	do
	{
		cout << "Enter numerator and then denominator for a rational number: ";
		cin >> r[i].num >> r[i].den;
		cout << "More rational numbers? (Y/N) ";
		cin >> ask;
		i++;
		more++;
	} while (ask == 'y' || ask == 'Y');
	return more;
}
void displayArray(rational r[], int n)
{
	for (int i = 0; i < n; i++)
	{
		int gcd = GCD(r[i]);
		int a = r[i].num / gcd;
		int b = r[i].den / gcd;
		if (b < 0)
		{
			a = a * (-1);
			b = b * (-1);
		}
		cout << a << "/" << b << "     ";
	}
}
void sortRationalNumbers(rational r[], int n)
{
	for (int pass = 1; pass < n; pass++)
	{
		for (int c = 0; c < n - pass; c++)
		{
			double a, b, d, e;
			a = r[c].num;
			b = r[c].den;
			d = r[c + 1].num;
			e = r[c + 1].den;
			double trial1, trial2;
			trial1 = a / b;
			trial2 = d / e;
			if (trial1 > trial2)
				swap(r[c], r[c + 1]);
			int small;
			small = findSmallestRationalNumber(r, c, n);
			swap(r[0], r[small]);
		}
	}
}
int findSmallestRationalNumber(rational r[], int first, int n)
{
	rational small = r[first];
	for (int i = first + 1; i < n; i++)
	{
		double a, b, c, d, e, f;
		a = r[i].num;
		b = r[i].den;
		c = a / b;
		d = r[first].num;
		e = r[first].den;
		f = d / e;
		if (c < f)
		{
			small = r[i];
			first = i;
		}
		else
		{
			small = r[first];
			first = first;
		}
	}
	return first;
}
void swap(rational &r1, rational &r2)
{
	double temp1, temp2;
	temp1 = r1.num;
	r1.num = r2.num;
	r2.num = temp1;
	temp2 = r1.den;
	r1.den = r2.den;
	r2.den = temp2;
}
int GCD(const rational &r)
{
	int a = 0, b = 0;
	int remainder = r.num % r.den;
	while (remainder != 0)
	{
		a = r.den;
		b = remainder;
		remainder = a % b;
	}
	return b;
}