c# .net Binary BigEndian

BinaryPrimitives.WriteXXXBigEndian

Program.cs

public class Program
{
    private static readonly int HEADER_SIZE = 5;
    private const ushort PACKET_ID_ECHO = 1;

    public static void Main(string[] args)
    {
        byte[] bytes = new byte[4];
        BinaryPrimitives.WriteUInt16BigEndian(bytes.AsSpan<byte>(0, 2), 7);
        BinaryPrimitives.WriteUInt16BigEndian(bytes.AsSpan<byte>(2, 2), 300);
        Console.WriteLine("{0}, {1}", bytes[0], bytes[1]);
        Console.WriteLine("{0}, {1}", bytes[2], bytes[3]);
  
        string data = @"{""a"":""hello""}";
        byte[] body = Encoding.UTF8.GetBytes(data);
        ushort totalSize = (ushort) (HEADER_SIZE + body.Length);

        bytes = new byte[totalSize];

        BinaryPrimitives.WriteUInt16BigEndian(new Span<byte>(bytes, 0, 2), totalSize);
        BinaryPrimitives.WriteUInt16BigEndian(new Span<byte>(bytes, 2, 2), PACKET_ID_ECHO);
        Buffer.BlockCopy(new byte[1], 0, bytes, 4, 1); // byte
        Buffer.BlockCopy(body, 0, bytes, HEADER_SIZE, body.Length);

        Console.WriteLine("{0}, {1}", bytes[0], bytes[1]);
        Console.WriteLine("{0}, {1}", bytes[2], bytes[3]);
    }
}

 

references
https://copyprogramming.com/howto/c-int-to-byte
https://learn.microsoft.com/ko-kr/dotnet/api/system.buffers.binary.binaryprimitives?view=net-8.0
https://stackoverflow.com/questions/59774345/correct-way-to-convert-between-basic-types-and-raw-bytes