How do I write ints out to a text file with the low bits on the right side (Bigendian)

Question

By default the BinaryWriter class writes int values with the low bits on the left (e.g. (int)6 becomes 06 00 00 00 when the resulting file is viewed in a hex editor). I need the low bits on the right (e.g. 00 00 00 06).

How do I achieve this?

EDIT: Thanks strager for giving me the name for what I was looking for. I've edited the title and tags to make it easier to find.

Answer 1

You are looking to change the Byte Order (aka Endianness). You want to print out big endian. Not sure how you'd do that in C#, but you can swap your bytes in the integer before sending it to the BinaryWritter class.

You can check the endianness of the current system using System.BitConverter.IsLittleEndian. I am not sure if BinaryWriter uses the system's endianness or little endian for compatibility.

Answer 2

Jon Skeet has an EndianBitConverter here that should do the job. Just use big/little endian as desired. Alternatively, just shift the data a few times ;-p

        int i = 6;
        byte[] raw = new byte[4] {
            (byte)(i >> 24), (byte)(i >> 16),
            (byte)(i >> 8), (byte)(i)};

Answer 3

Not really a built in way but you can use this: EndianBit*. Thanks to Jon Skeet :P

Answer 4

If you're determined to use something built in, there are a number of overloads of System.Net.IPAddress.HostToNetworkOrder().

These will do what you want because it's overwhelmingly likely that 'host' order is always little-endian, and 'network' order is big-endian, which is what you want.

Bit of a hack to use these though, if you're not doing anything at all to do with networking.

Answer 5

You could also use the BitConverter to get a byte array, then reverse it. Something like:

Byte[] bytes = BitConverter.GetBytes(number);
Array.Reverse(bytes);

// Then, to write the values you use
writer.Write(bytes);

Answer 6

It won't help now, but I created a connect ticket for BinaryReder/Writer to support Bigendian out the box. Go vote for it here.