How can I convert a UInt32[] and a Int32[] array to byte arrays?

Question

Trying to create a function that converts objects to byte arrays (without the overhead/metadata things like BinaryFormatter create). I think I'm happy with the following code except the ability of it to convert UInt32[] arrays and Int32[] arrays to a byte array.

private byte[] ObjectToByteArray(object obj)
{
    string dataType = obj.GetType().Name;
    switch (dataType)
    {
        case "Byte[]": // an array of bytes
            return (byte[])obj;
        case "String": // a null-terminated ASCII string
            return Encoding.ASCII.GetBytes((string)obj);
        case "UInt16": // an array of unsigned short (16-bit) integers
            return BitConverter.GetBytes((ushort)obj);
        case "UInt32": // an array of unsigned long (32-bit) integers
            return BitConverter.GetBytes((uint)obj);
        case "UInt32[]": // an array of pairs of unsigned long (32-bit) integers
            //return BitConverter.GetBytes((ushort)obj);
            return null;
        case "Int32": // an array of signed long (32-bit) integers
            return BitConverter.GetBytes((int)obj);
        case "Int32[]": // an array of pairs of signed long (32-bit) integers
            //return BitConverter.GetBytes((int)obj);
            return null;
        default:
            throw new Exception($"The type of value ({dataType}) is not supported.");
    }
}

I was thinking of doing something like a simple for each 4 bytes loop and keep adding them to a byte array but was unsure if that would work or even be the best approach. I'm not even sure my current method is the best approach for what I have already made. Everything I have found on the web seems to confuse me and make my head spin when dealing with converting data types.

Answer 1

    public static byte[] ToByteArray<T>(T[] obj) where T : unmanaged
    {
        var tgt = new byte[Buffer.ByteLength(obj)];
        Buffer.BlockCopy(obj, 0, tgt, 0, tgt.Length);
        return tgt;
    }

Mind Endianess of returned array. It is not safe to serialize it in LittleEndian (windows) and deserialize in BigEndian (linux/mac) and visa-versa. Nor its derivatives like hashes, etc. It's for in-memory use only.

This can be made stable if iterated manually using BinaryPrimitives. They default to BigEndian for both read/write on all systems.