C++program to delete the content of a Binary File

// C++ program to delete the record
// of a binary file

#include <bits/stdc++.h>

using namespace std;

class abc {
    int roll;
    char name[20];

public:
    void deleteit(int);
    void testcase1();
    void testcase2();
    void putdata();
};

// Code to display the data of the
// data of the object
void abc::putdata()
{
    cout << "roll no: ";
    cout << roll;
    cout << "\nname: ";
    cout << name;
}

// code to delete
// the content of the binary file
void abc::deleteit(int rno)
{

    int pos, flag = 0;

    ifstream ifs;
    ifs.open("he.dat", ios::in | ios::binary);

    ofstream ofs;
    ofs.open("temp.dat", ios::out | ios::binary);

    while (!ifs.eof()) {

        ifs.read((char*)this, sizeof(abc));

        // if(ifs)checks the buffer record in the file
        if (ifs) {

            // comparing the roll no with
            // roll no of record to be deleted
            if (rno == roll) {
                flag = 1;
                cout << "The deleted record is \n";

                // display the record
                putdata();
            }
            else {
                // copy the record of "he" file to "temp" file
                ofs.write((char*)this, sizeof(abc));
            }
        }
    }

    ofs.close();
    ifs.close();

    // delete the old file
    remove("he.dat");

    // rename new file to the older file
    rename("temp.dat", "he.dat");

    if (flag == 1)
        cout << "\nrecord successfully deleted \n";
    else
        cout << "\nrecord not found \n";
}

// Sample input 1
void abc::testcase1()
{
    int rno;

    // roll no to be searched
    rno = 1;

    // call deleteit function
    // with the roll no. of record to be deleted
    deleteit(rno);
}

// Sample input 2
void abc::testcase2()
{
    int rno;

    // roll no to be searched
    rno = 4;

    // call deleteit function
    // with the roll no of record to be deleted
    deleteit(rno);
}

// Driver code
int main()
{
    abc s;

    // sample case 1
    s.testcase1();

    // sample case 2

    s.testcase2();

    return 0;
}