#include <iostream>
#include <fstream>
using namespace std;

int ncd(int a, int b) {
	return (b == 0 ? a : ncd(b, a % b));
}

struct Drib {
	int ch;
	int zn;

	void init() {
		cout << "\nInput ch: ";
		cin >> ch;
		cout << "Input zn: ";
		cin >> zn;
		skor();
	}
	void skor() {
		int d = ncd(ch, zn);
		if (d != 0) {
			ch /= d;
			zn /= d;
		}
	}
	void print() {
		cout << ch << "/" << zn << endl;
	}

};
int main()
{
	Drib a;
	Drib* pDrip = new Drib;
	fstream finOut;

	finOut.open("info.dat", ios::binary | ios::out);//ios::out|ios::trunc);
	if (!finOut.is_open()) {
		cerr << "\n Error opening file(out)!!\n";
		system("pause");
		return 1;
	}
	int vUser;
	do {

		a.init();
		pDrip->init();
		finOut.write((char*)pDrip, sizeof(Drib));
		//finOut.write(reinterpret_cast<char*>(&a), sizeof(a));
		finOut.write((char*)(&a), sizeof(Drib));
		cout << "\n Create a fraction?(1/Yes  0/No) ";
		cin >> vUser;
	} while (vUser);
	finOut.close();

	/*ifstream fIn;
	finOut.open("info.dat", ios::binary );*/

	finOut.open("info.dat", ios::binary | ios::in);
	if (!finOut.is_open()) {
		cerr << "\n Beda(in)!!";
		system("pause");
		return 1;
	}
	cout << "\nRead fractions in file:\n";
	finOut.read((char*)(&a), sizeof(a));//1 Drip
	while (finOut.good()) {//!finOut.eof()
		a.print();
		finOut.read(reinterpret_cast<char*>(&a), sizeof(a));
	}
	finOut.close();
	system("pause");
	Drib* p;
	finOut.open("info.dat", ios::binary | ios::in);
	if (!finOut.is_open()) {
		cerr << "\n Error opening file(in)!!";
		system("pause");
		return 1;
	}
	finOut.seekg(0, ios::end);//ios::beg ios::cur
	int endpos = (int)finOut.tellg();
	int n = endpos / sizeof(Drib);
	cout << "\n There are  " << n << " fractions in the file\n";
	if (n == 0) {
		return 0;
	}
	finOut.seekg(0);//finOut.seekg(0, ios::beg);
	p = new Drib[n];
	int i = 0;
	for (i = 0; i < n; ++i) {
		finOut.read(reinterpret_cast<char*>(p + i), sizeof(Drib));
	}

	cout << "Counted " << i << " fractions\n";
	for (i = 0; i < n; ++i) {
		p[i].print();

	}

	//finOut.seekg(sizeof(drob)*(n-1));
	finOut.seekg(-(streamoff)sizeof(Drib), ios::end);
	finOut.read(reinterpret_cast<char*>(&a), sizeof(Drib));
	cout << "\n The last fraction:\n";
	a.print();
	delete[] p;
	finOut.close();
	a.init();
	finOut.open("info.dat", ios::binary | ios::app);
	finOut.write((char*)(&a), sizeof(a));
	//finOut.seekp(0, ios::end);
	endpos = (int)finOut.tellp();
	n = endpos / sizeof(Drib);
	cout << "\n There are  " << n << " fractions in the file\n";
	finOut.close();
	finOut.open("info.dat", ios::binary | ios::in);
	if (!finOut.is_open()) {
		cerr << "\n Error: bad open file(in)!!";
		system("pause");
		return 1;
	}
	finOut.seekg(-(streamoff)sizeof(Drib), ios::end);
	finOut.read(reinterpret_cast<char*>(&a), sizeof(Drib));
	cout << "\n The last fraction:\n";
	a.print();
}