// File: ex8-12.cpp - File I/O read() and write()

#include <fstream>
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <cstring>
#include <string>
using namespace std;

class Employee
{
public:
	Employee() : age(0), salary(0.f) {}
private:
	char empno[8];
	char name[32];
	unsigned short age;
	float salary;
	friend istream& operator>>(istream&, Employee&);
	friend ostream& operator<<(ostream&, const Employee&);
};

istream& operator>>(istream& in, Employee& E)
{
	in >> E.empno >> E.name >> E.age >> E.salary;
	return in;
}

ostream& operator<<(ostream& out, const Employee& E)
{
	out << setprecision(2) << fixed << showpoint << left;
	out << setw(8) << E.empno
		<< setw(13) << E.name
		<< right << setw(3) << E.age
		<< setw(10) << E.salary;
	return out;
}


class EmployeeFile
{
public:	
	EmployeeFile(string filename = "empfile");
	void print();								// Why not const?
	void open_for_read_write();
	void close() { File.close(); }
	bool operator!() const { return !File.rdstate(); }
private:
	string Filename;
	fstream File;
	friend EmployeeFile& operator>>(EmployeeFile&, Employee&);
	friend EmployeeFile& operator<<(EmployeeFile&, const Employee&);
};


EmployeeFile::EmployeeFile(string filename) 
: Filename(filename), File(filename.c_str(),ios::out|ios::binary)
{
}

void EmployeeFile::print()
{
	Employee temp;

	// position to the beginning of the file
	File.seekg(0,ios_base::beg);

	// read data from the file and print out each Employee record
	while (!(*this>>temp)) {
		cout << temp << endl;
	}

	// clear the File stream state (after reading EOF)
	File.clear();
}

void EmployeeFile::open_for_read_write()
{
	File.open(Filename.c_str(),ios::in | ios::out | ios::binary);	

	if (File.fail() ) {
		cerr << "Unable to open Employee file: " << Filename << endl;
		exit(-1);
	}
}

EmployeeFile& operator>>(EmployeeFile& EF, Employee& E)
{
	EF.File.read((char*) &E, sizeof E);
	return EF;
}

EmployeeFile& operator<<(EmployeeFile& EF, const Employee& E)
{
	EF.File.write((char*) &E, sizeof E);
	return EF;
}

int main()
{
	Employee temp;
	EmployeeFile EmpFile("employee.dat");
	
	for (int i = 0; i<4; ++i) {
		cout << "Enter empno name age salary\n";
		cin >> temp;
		EmpFile << temp;
	}

	// close the file and reopen it in read-write mode
	EmpFile.close();
	EmpFile.open_for_read_write();

	EmpFile.print();
	return 0;
}