// Program to overload stream operators for Student class (use files).
// Assignment-34
// soovrld.cpp, Author - Krishna Kumar Khatri.

// Uncomment ONLY the following line if you are using Turbo/Borland compiler.
// #define TC
#ifdef TC
	#include <fstream.h>	
	#include <string.h>
#else
	#include <iostream>
	#include <fstream>
	#include <cstring>
	using namespace std;
#endif
#include <conio.h>  // For getch.
const int MAXLEN = 50;

class Student
{
        int rollno;
        char name[MAXLEN];
        float marks;
        char filename[MAXLEN/2];
    public:
        Student(char* fn = 0)
            { strcpy(filename, fn); }
        friend istream& operator>>(istream&, Student&);
        friend ostream& operator<<(ostream&, const Student&);
};

istream& operator>>(istream& is, Student& st)
{
    ofstream fn;
    cout << "Enter Roll no.: "; is >> st.rollno;
    cout << "Name: "; is >> st.name;
    cout << "Marks: "; is >> st.marks;
	fn.open(st.filename, ios::app);
    fn.write((char*)&st, sizeof(st));
    fn.close();
    return is;
}

ostream& operator<<(ostream& os, const Student& st)
{
    ifstream fn(st.filename);
    fn.read((char*)&st, sizeof(st));
    while (!fn.eof()) {
        os << endl << endl 
           << "Roll no. - " << st.rollno << endl;
        os << "Name     - " << st.name << endl;
        os << "Marks    - " << st.marks;
        fn.read((char*)&st, sizeof(st));
    }
    return os;
}

int main()
{
    #ifdef TC
        clrscr();
    #endif
    char filename[MAXLEN/2] = "Student.txt";
    Student st(filename);
    int choice = 'y';
    
    do {
        cout << "Enter data," << endl;
        cin >> st;
        cout << endl << "Continue insertion (y/n): ";
        choice = getche();
        cout << endl << endl;
    } while (choice == 'y');
    
    cout << "Saved data read as,";
    cout << st;

    cout << endl << endl << "Program over. Press any key to exit...";
    getch();
    return 0; // Successful termination.
}