Reversing byte order in .NET

Question

In the code below, why do X and Y take on different values than what I would think intuitively?

If the bytes 0-7 are written to the buffer, shouldn\'t the resulting

Answer 1

BinaryReader assumes Little Endian order: http://msdn.microsoft.com/en-us/library/system.io.binaryreader.readint64.aspx