How 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 are there any considerations to take when writing to the end of a binary file? thanks a lot for your help.

Answer 1

Use File.OpenWrite in conjunction with Stream.Write.

using (Stream file = File.OpenWrite(@"C:\path\to\somefile.bin"))
{
    file.Write(someBytes, 0, someBytes.Length);
}

However, there are considerations to think about when appending to a binary file. Typically, binary files are taken as a whole. To append data to a binary file could destroy the ability for applications that rely on this data to access the information after you've appended your data to the same file. I'd recommend not appending the data to an existing file, but instead to add the data to it's own new file. This will make it far easier to use the data.

Answer 2

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

Answer 3

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...