I have a C# NETMF project, and I need to convert a float to a byte[] and vice versa. The problem is, NETMF doesn't have System.BitConverter like .NET, so I can't really find any way of doing it without going low level and doing it myself.
I have always programmed high-level (Java, Python, C#, etc.) and have only dabbled in C++, so I don't really know how to turn a float into a byte array.
What would some sample code of a boilerplate function for doing this look like?
The StructLayoutAttribute is supported by the .NET Micro Framework, so you could use a C++ style union to get the bytes of a float (and the other way around too):
[StructLayout(LayoutKind.Explicit)]
public struct FloatUnion
{
[FieldOffset(0)] public float Value;
[FieldOffset(0)] public byte Byte0;
[FieldOffset(1)] public byte Byte1;
[FieldOffset(2)] public byte Byte2;
[FieldOffset(3)] public byte Byte3;
public byte[] ToByteArray()
{
return new[] { Byte0, Byte1, Byte2, Byte3 };
}
public static byte[] FloatToBytes(float value)
{
return new FloatUnion { Value = value }.ToByteArray();
}
public static float BytesToFloat(byte[] bytes)
{
if (bytes.Length != 4) throw new ArgumentException("You must provide four bytes.");
return new FloatUnion { Byte0 = bytes[0], Byte1 = bytes[1], Byte2 = bytes[2], Byte3 = bytes[3] }.Value;
}
}
Unlike the integers (Int32, Byte, UInt64, etc) where each value is easily determined from the status of each bit in the integer's bytes, there is no intuitive representation of a floating-point number in binary, so the IEEE defined a specification for floating point numbers: IEEE-754. Suffice to say, it isn't simple, but following the rules in the specification will allow you to serialize a .NET System.Single and System.Double instance to a series of bytes.
The desktop .NET Framework actually cheats here. The GetBytes(Single) function actually just casts the Single instance to an Int32 then copies the raw bytes into a 4-byte array using raw pointers. However you can't take this useful shortcut because the micro framework does not support pointers - even worse: the MF doesn't include BinaryWriter either. You'll have to roll your own IEEE-754 serializer I'm afraid.
Use a BinaryWriter on top of a MemoryStream.
