How to append data to a binary file?

Question

I have a binary file to which I want to append a chunk of data at the end of the file, how can I achieve this using C# and .net? Also is there anything to consider when wri

Answer 1

Using StreamWriter and referencing DotNetPerls, make sure to add the True boolean to the StreamWriter constructor, if otherwise left blank, it'll overwrite as usual:

using System.IO;

class Program
{
    static void Main()
    {
    // 1: Write single line to new file
    using (StreamWriter writer = new StreamWriter("C:\\log.txt", true))
    {
        writer.WriteLine("Important data line 1");
    }
    // 2: Append line to the file
    using (StreamWriter writer = new StreamWriter("C:\\log.txt", true))
    {
        writer.WriteLine("Line 2");
    }
    }
}

Output
    (File "log.txt" contains these lines.)

Important data line 1
Line 2

This is the solution that I was actually looking for when I got here from Google, although it wasn't a binary file though, hope it helps someone else.

Answer 2

You should be able to do this via the Stream:

using (FileStream data = new FileStream(path, FileMode.Append))
{
    data.Write(...);
}

As for considerations - the main one would be: does the underlying data format support append? Many don't, unless it is your own raw data, or text etc. A well-formed xml document doesn't support append (without considering the final end-element), for example. Nor will something like a Word document. Some do, however. So; is your data OK with this...

Answer 3

private static void AppendData(string filename, int intData, string stringData, byte[] lotsOfData)
{
    using (var fileStream = new FileStream(filename, FileMode.Append, FileAccess.Write, FileShare.None))
    using (var bw = new BinaryWriter(fileStream))
    {
        bw.Write(intData);
        bw.Write(stringData);
        bw.Write(lotsOfData);
    }
}