Turbo C++ File Handling: Stuck in input loop

I am making a program in turbo C++ to create student records and modify/delete them in a binary file on user's command.

The main class that is needed to know is the student class:

class student
{
private:
    int roll_no;
    char name[50];
    academic ac;
    co_curricular cc;

    void calculate();

public:
    int get_data(int);
    void show_data();
    void show_tabular();

    int ret_roll_no();
};

There is some problem with the get_data() function, specially in the part where the roll number is assigned. The logic to assign the roll number is:

student temp;
fstream fp;
roll_no = random(9000) + 1000;

//Checking if roll number is unique
fp.open("STUDENT.DAT", ios::in);
while(!fp.eof())
{
    fp.read((char*)&temp, sizeof(temp));
    if(roll_no == temp.ret_roll_no())
        roll_no = random(9000) + 1000;  //Set roll number to another random value
}
fp.close();

Binary file STUDENT.DAT already exists, but the code doesn't go after the loop. It is somehow stuck.

Please help