c++ - 将 float 数组转换到 char* 或从 char* 转换并通过网络发送

Question

这就是我到目前为止所做的一切:

struct HeadPacket
{
  int type;
};

struct ReceivePacket
{
  // Header
  HeadPacket Head;
  // Raw Data
  char* buffer;
};
struct MovePacket
{
  // Header
  HeadPacket Head;
  // Raw Data
  float X;
  float Y;
};
struct ClientsPacket
{
  // Header
  HeadPacket Head;
  // Raw Data
  int Clients;
  float* X;
  float* Y;
};

这些是我拥有的一些示例数据包。

首先我创建一个数据包，将其转换为 char* 并发送。

MovePacket m;
m.Head.type = 2;
m.X = X;
m.Y = Y;
this->Socket->Send(this->Socket->GetAddress(), (char*)&m, sizeof(m));

在另一边我收到它:

char packet[256]; //max size of a packet
SOCKADDR_IN server;
this->Socket->Receive(packet, 256, &server);

现在我将它转换为一个数据包以读取类型，然后我进一步转换它

    ReceivePacket* rec = (ReceivePacket*)packet;
    switch (rec->Head.type)
{
    case 0:
    {
     MovePacket* move = (MovePacket*)rec;
    }
    break;
    case 1:
    {
     ClientsPacket* c = (ClientsPacket*)rec;
    }
    break;
}

如果我发送和接收 MovePacket，一切正常。

但是，如果我发送一个具有 float 组的 ClientsPacket，则 float 组永远不会包含正确的值。

    ClientsPacket c;
    c.Head.type = 3;
    c.Clients = clients.size();
    c.Y = new float[clients.size()];
    c.X = new float[clients.size()];

    int size = sizeof(c.Head) + sizeof(int)+((sizeof(float)*clients.size()) * 2);
    for (unsigned int i = 0; i < clients.size(); i++)
    {
      c.X[i] = clients[i].X;
      c.Y[i] = clients[i].Y;
      printf("X: %f Y: %f\n", c.Y[i], c.X[i]);
    }
    rc = sock.Send(newclient.GetAddr(), (char*)&c, size);

您知道如何修复它吗？我在哪里可以进一步阅读它为什么会发生，或者您能向我解释为什么会发生吗？

Answer 1

它真正应该是什么样子:服务器:

  ClientsPacket c;
    c.Head.type = 3;
    c.Clients = clients.size();
    c.X = new float[clients.size()];
    c.Y = new float[clients.size()];
    //define sizes
    int fsize = (sizeof(float)*clients.size());
    int hsize = sizeof(c.Head) + sizeof(c.Clients);
    int size = hsize + sizeof(float)+(fsize*2);
    //define sendchar
    char* buffer = new char[size];
    //fill arrays
    for (unsigned int i = 0; i < clients.size(); i++)
    {
      c.X[i] = clients[i].X;
      c.Y[i] = clients[i].Y;
      printf("X: %f Y: %f\n", c.X[i], c.Y[i]);
    }
    //copy memory from client 
    memcpy(buffer, &c, hsize);
    memcpy(buffer + hsize, c.X, fsize);
    memcpy(buffer + hsize + fsize, c.Y, fsize);

客户:

ClientsReceivePacket* cv = (ClientsReceivePacket*)rec;

      ClientsPacket c;
      memcpy(&c.Head, packet, sizeof(c.Head));
      memcpy(&c.Clients, packet + sizeof(c.Head), sizeof(c.Clients));
      c.X = new float[cv->Clients];
      c.Y = new float[cv->Clients];
      //define sizes
      int hsize = sizeof(c.Head) + sizeof(c.Clients);
      int fsize = (sizeof(float)*c.Clients);
      //copy content into float array
      memcpy(c.X, packet + hsize, fsize);
      memcpy(c.Y, packet + hsize + fsize, fsize);