Question

是否可以将浮动从大端转换为小端？我有一个来自大端程序平台的值，我通过UDP发送到Windows进程（little endian）。这个值是一个浮点数，但是当我尝试BitConverter.ToSingle时，我总是得到5.832204E-42，但它应该是36.000。

我做错了什么？

这是一段剪辑代码：

// Receive thread
private void ReceiveData()
{
    int count = 0;

    IPEndPoint remoteIP = new IPEndPoint(IPAddress.Parse("10.0.2.213"), port);
    client = new UdpClient(remoteIP);
    while (true)
    {
        try
        {
            IPEndPoint anyIP = new IPEndPoint(IPAddress.Any, 0);
            byte[] data = client.Receive(ref anyIP);

            float x = BitConverter.ToSingle(data, 0);
            float y = BitConverter.ToSingle(data, 4);
            float z = BitConverter.ToSingle(data, 8);
            float alpha = BitConverter.ToSingle (data, 12);
            float theta = BitConverter.ToSingle (data, 16);
            float phi = BitConverter.ToSingle (data, 20);

            print(">> " + x.ToString() + ", "+ y.ToString() + ", "+ z.ToString() + ", " +
                  alpha.ToString() + ", "+ theta.ToString() + ", "+ phi.ToString());

            // Latest UDP packet
            lastReceivedUDPPacket=x.ToString()+" Packet#: "+count.ToString();
            count = count+1;
        }

Answer 1

36.0和5.832204E-42是endian-obposites，因此这是一个字节序问题。在Windows / .NET上，你通常是little-endian，所以我猜测数据是big-endian。这意味着您需要分别为每个值反转（而不是整个数组）。

要以CPU安全的方式编写，最好选择BitConverter.IsLittleEndian，并在必要时进行补偿。例如：

public static float ReadSingleBigEndian(byte[] data, int offset)
{
    return ReadSingle(data, offset, false);
}
public static float ReadSingleLittleEndian(byte[] data, int offset)
{
    return ReadSingle(data, offset, true);
}
private static float ReadSingle(byte[] data, int offset, bool littleEndian)
{
    if (BitConverter.IsLittleEndian != littleEndian)
    {   // other-endian; reverse this portion of the data (4 bytes)
        byte tmp = data[offset];
        data[offset] = data[offset + 3];
        data[offset + 3] = tmp;
        tmp = data[offset + 1];
        data[offset + 1] = data[offset + 2];
        data[offset + 2] = tmp;
    }
    return BitConverter.ToSingle(data, offset);
}

使用：

float x= ReadSingleBigEndian(data, 0);
float y= ReadSingleBigEndian(data, 4);
float z= ReadSingleBigEndian(data, 8);
float alpha= ReadSingleBigEndian(data, 12);
float theta= ReadSingleBigEndian(data, 16);
float phi= ReadSingleBigEndian(data, 20);

使用C＃将big endian的float值转换为little endian

1 个答案: