C++ - File Streams and Binary File Handling in C++

File handling in C++ allows programs to store data permanently in files instead of keeping it only in memory. This is useful when a program needs to save information so that it can be used again later. C++ provides file handling through the fstream library.

There are mainly three classes used for file operations:

1. ifstream – Used to read data from a file.

2. ofstream – Used to write data to a file.

3. fstream – Used for both reading and writing.

To use file streams, the header file must be included.

#include <fstream>

Text files store data in human-readable form, while binary files store data in raw binary format. Binary files are faster and more efficient for storing structured data such as objects.

Opening a file in C++ can be done using the open() function or directly while creating the object.

Example of writing to a text file:

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

int main() {
    ofstream file("data.txt");
    file << "Welcome to C++ File Handling";
    file.close();
    return 0;
}

Example of reading from a text file:

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

int main() {
    ifstream file("data.txt");
    string text;

    while(getline(file, text)) {
        cout << text << endl;
    }

    file.close();
    return 0;
}

Binary file handling is used when storing data like structures or objects. Instead of writing text, the program writes the actual memory representation of data.

Example of writing to a binary file:

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

struct Student {
    int id;
    char name[20];
};

int main() {
    Student s = {1, "Rahul"};
    ofstream file("student.dat", ios::binary);
    file.write((char*)&s, sizeof(s));
    file.close();
    return 0;
}

Example of reading from a binary file:

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

struct Student {
    int id;
    char name[20];
};

int main() {
    Student s;
    ifstream file("student.dat", ios::binary);
    file.read((char*)&s, sizeof(s));

    cout << s.id << " " << s.name;
    file.close();
    return 0;
}

Binary files are commonly used in applications such as databases, game development, and systems programming because they allow fast storage and retrieval of structured data.

In summary, file streams in C++ help programs read and write data to files, while binary file handling provides a more efficient way to store and manage complex data structures.