How to copy one Stream to a byte array with the smallest C# code?

Question

Until now I am counting 12 LoCs. Could you make it smaller?

using (Stream fileStream = File.OpenRead(fileName))
{
    using (BinaryReader binaryReader = new BinaryReader(fileStream))
    {
        using (MemoryStream memoryStream = new MemoryStream())
        {
            byte[] buffer = new byte[256];
            int count;
            int totalBytes = 0;
            while ((count = binaryReader.Read(buffer, 0, 256)) > 0)
            {
                memoryStream.Write(buffer, 0, count);
                totalBytes += count;
            }
            memoryStream.Position = 0;
            byte[] transparentPng = new byte[totalBytes];
            memoryStream.Read(transparentPng, 0, totalBytes);
        }
    }
}

Answer 1

There's a static method that can do this for you in one call.

var data = File.ReadAllBytes(fileName);

Alternatively, a method that works for any Stream (that returns its length) would be:

byte[] data;
using (var br = new BinaryReader(stream))
    data = br.ReadBytes((int)stream.Length);

For streams that don't have a well-defined length (e.g. NetworkStream), and thus raise an exception on calling stream.Length, this of course does not work. The slightly more complicated solution presented in Jon Skeet's answer is then what you probably want.