BinaryReader and BinaryWriter in C#

What are BinaryReader and BinaryWriter in C#?

**BinaryReader** and **BinaryWriter** are classes in the System.IO namespace that allow reading and writing binary data to files. These classes provide an efficient way to store and retrieve structured binary data such as numbers, text, and custom objects.

Key Features of BinaryReader & BinaryWriter

Efficient for handling **binary data** like numbers and images.
Stores **structured data** in a compact format.
Supports **primitive data types** such as integers, floats, and strings.
Avoids the overhead of **text encoding and parsing**.

Writing Binary Data Using BinaryWriter

The BinaryWriter class allows writing binary data to a file efficiently.

Example: Writing Binary Data

using System;
using System.IO;

class Program
{
    static void Main()
    {
        string filePath = "data.bin";

        using (BinaryWriter writer = new BinaryWriter(File.Open(filePath, FileMode.Create)))
        {
            writer.Write(42);             // Writing an integer
            writer.Write(3.14);           // Writing a double
            writer.Write("Hello C#");     // Writing a string
        }

        Console.WriteLine("Binary data written successfully.");
    }
}

// Output:
// Binary data written successfully.

The BinaryWriter class writes data in **binary format**, making it more compact.

Reading Binary Data Using BinaryReader

The BinaryReader class is used to **read structured binary data** from a file.

Example: Reading Binary Data

using System;
using System.IO;

class Program
{
    static void Main()
    {
        string filePath = "data.bin";

        using (BinaryReader reader = new BinaryReader(File.Open(filePath, FileMode.Open)))
        {
            int number = reader.ReadInt32();       // Reading an integer
            double pi = reader.ReadDouble();       // Reading a double
            string message = reader.ReadString();  // Reading a string

            Console.WriteLine($"Number: {number}");
            Console.WriteLine($"Double: {pi}");
            Console.WriteLine($"Message: {message}");
        }
    }
}

// Output:
// Number: 42
// Double: 3.14
// Message: Hello C#

The **order of reading should match the order of writing**, ensuring data integrity.

Writing and Reading Custom Objects Using BinaryWriter & BinaryReader

You can store structured objects in binary format using **BinaryWriter** and **BinaryReader**.

Example: Writing and Reading Custom Objects

using System;
using System.IO;

class Person
{
    public string Name { get; set; }
    public int Age { get; set; }

    public void WriteToBinary(BinaryWriter writer)
    {
        writer.Write(Name);
        writer.Write(Age);
    }

    public static Person ReadFromBinary(BinaryReader reader)
    {
        return new Person
        {
            Name = reader.ReadString(),
            Age = reader.ReadInt32()
        };
    }
}

class Program
{
    static void Main()
    {
        string filePath = "person.bin";

        // Writing object data
        using (BinaryWriter writer = new BinaryWriter(File.Open(filePath, FileMode.Create)))
        {
            Person person = new Person { Name = "Alice", Age = 30 };
            person.WriteToBinary(writer);
        }

        // Reading object data
        using (BinaryReader reader = new BinaryReader(File.Open(filePath, FileMode.Open)))
        {
            Person person = Person.ReadFromBinary(reader);
            Console.WriteLine($"Name: {person.Name}, Age: {person.Age}");
        }
    }
}

// Output:
// Name: Alice, Age: 30

The **WriteToBinary()** and **ReadFromBinary()** methods ensure structured object persistence.

Best Practices for Using BinaryReader & BinaryWriter

Use **BinaryWriter** when writing structured binary data to avoid unnecessary text overhead.
Always **read data in the same order** as it was written.
Ensure **file integrity** by handling exceptions with try-catch.
Use **FileMode.Append** when appending binary data instead of overwriting.

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