How to Append a Byte Array to the End of a Binary File in C#?

How do I append a byte array to the end of a binary file in C#?

byte[] dataToAppend = new byte[] { 1, 2, 3, 4, 5 }; // Example byte array
using (FileStream fs = new FileStream("example.bin", FileMode.Append, FileAccess.Write))
{
    fs.Write(dataToAppend, 0, dataToAppend.Length);
}

Appending a byte array to a binary file in C# is straightforward using the FileStream class. This process involves opening the file in append mode, writing the byte array, and closing the stream. Here's how to do it step-by-step:

using System;
using System.IO;

class Program
{
    static void Main()
    {
        // The byte array you want to append
        byte[] dataToAppend = new byte[] { 1, 2, 3, 4, 5 };

        // Open the file and append the data
        using (FileStream fs = new FileStream("example.bin", FileMode.Append, FileAccess.Write))
        {
            fs.Write(dataToAppend, 0, dataToAppend.Length);
        }
        Console.WriteLine("Data appended successfully.");
    }
}

Causes

• You need to ensure that the binary file exists before appending data to it.
• File permissions should allow for writing, or an exception will be thrown.

Solutions

• Use FileMode.Append when creating the FileStream to ensure data is added to the end of the file.
• Confirm that the byte array is initialized and populated with the correct data before writing.

Mistake: Forgetting to check if the file exists before appending data.

Solution: Use File.Exists before the operation to verify the file's existence.

Mistake: Not handling exceptions that may occur during file access.

Solution: Wrap the file handling code in a try-catch block to manage potential IO exceptions.

Mistake: Using the wrong FileMode, which can result in overwriting existing data.

Solution: Always use FileMode.Append to ensure that you only add data to the end of the file.