An elegant way to consume (all bytes of a) BinaryReader?

Question

Is there an elegant to emulate the StreamReader.ReadToEnd method with BinaryReader? Perhaps to put all the bytes into a byte array?

I do this:

read1.ReadBytes((int)read1.BaseStream.Length);

...but there must be a better way.

Answer 1

Original Answer (Read Update Below!)

Simply do:

byte[] allData = read1.ReadBytes(int.MaxValue);

The documentation says that it will read all bytes until the end of the stream is reached.

---

Update

Although this seems elegant, and the documentation seems to indicate that this would work, the actual implementation (checked in .NET 2, 3.5, and 4) allocates a full-size byte array for the data, which will probably cause an OutOfMemoryException on a 32-bit system.

Therefore, I would say that actually there isn't an elegant way.

Instead, I would recommend the following variation of @iano's answer. This variant doesn't rely on .NET 4:
Create an extension method for BinaryReader (or Stream, the code is the same for either).

public static byte[] ReadAllBytes(this BinaryReader reader)
{
    const int bufferSize = 4096;
    using (var ms = new MemoryStream())
    {
        byte[] buffer = new byte[bufferSize];
        int count;
        while ((count = reader.Read(buffer, 0, buffer.Length)) != 0)
            ms.Write(buffer, 0, count);
        return ms.ToArray();
    }
    
}

Answer 2

There is not an easy way to do this with BinaryReader. If you don't know the count you need to read ahead of time, a better bet is to use MemoryStream:

public byte[] ReadAllBytes(Stream stream)
{
    using (var ms = new MemoryStream())
    {
        stream.CopyTo(ms);
        return ms.ToArray();
    }
}

To avoid the additional copy when calling ToArray(), you could instead return the Position and buffer, via GetBuffer().

Answer 3

To copy the content of a stream to another, I've solved reading "some" bytes until the end of the file is reached:

private const int READ_BUFFER_SIZE = 1024;
using (BinaryReader reader = new BinaryReader(responseStream))
{
    using (BinaryWriter writer = new BinaryWriter(File.Open(localPath, FileMode.Create)))
    {
        int byteRead = 0;
        do
        {
            byte[] buffer = reader.ReadBytes(READ_BUFFER_SIZE);
            byteRead = buffer.Length;
            writer.Write(buffer);
            byteTransfered += byteRead;
        } while (byteRead == READ_BUFFER_SIZE);                        
    }                
}

Answer 4

Had the same problem.
First, get the file's size using FileInfo.Length.
Next, create a byte array and set its value to BinaryReader.ReadBytes(FileInfo.Length). e.g.

var size = new FileInfo(yourImagePath).Length;
byte[] allBytes = yourReader.ReadBytes(System.Convert.ToInt32(size));

Answer 5

Another approach to this problem is to use C# extension methods:

public static class StreamHelpers
{
   public static byte[] ReadAllBytes(this BinaryReader reader)
   {
      // Pre .Net version 4.0
      const int bufferSize = 4096;
      using (var ms = new MemoryStream())
      {
        byte[] buffer = new byte[bufferSize];
        int count;
        while ((count = reader.Read(buffer, 0, buffer.Length)) != 0)
            ms.Write(buffer, 0, count);
        return ms.ToArray();
      }

      // .Net 4.0 or Newer
      using (var ms = new MemoryStream())
      {
         stream.CopyTo(ms);
         return ms.ToArray();
      }
   }
}

Using this approach will allow for both reusable as well as readable code.

Answer 6

I use this, which utilizes the underlying BaseStream property to give you the length info you need. It keeps things nice and simple.

Below are three extension methods on BinaryReader:

• The first reads from wherever the stream's current position is to the end
• The second reads the entire stream in one go
• The third utilizes the Range type to specify the subset of data you are interested in.

public static class BinaryReaderExtensions {

    public static byte[] ReadBytesToEnd(this BinaryReader binaryReader) {
    
        var length = binaryReader.BaseStream.Length - binaryReader.BaseStream.Position;
        return binaryReader.ReadBytes((int)length);
    }
    
    public static byte[] ReadAllBytes(this BinaryReader binaryReader) {
    
        binaryReader.BaseStream.Position = 0;
        return binaryReader.ReadBytes((int)binaryReader.BaseStream.Length);
    }

    public static byte[] ReadBytes(this BinaryReader binaryReader, Range range) {

        var (offset, length) = range.GetOffsetAndLength((int)binaryReader.BaseStream.Length);
        binaryReader.BaseStream.Position = offset;
        return binaryReader.ReadBytes(length);      
    }
}

Using them is then trivial and clear...

// 1 - Reads everything in as a byte array
var rawBytes = myBinaryReader.ReadAllBytes();

// 2 - Reads a string, then reads the remaining data as a byte array
var someString = myBinaryReader.ReadString();
var rawBytes = myBinaryReader.ReadBytesToEnd();

// 3 - Uses a range to read the last 44 bytes
var rawBytes = myBinaryReader.ReadBytes(^44..);