用WM_COPYDATA传递struct

    利用WM_COPYDATA可以轻松实现两个进程间的通信，但是一般都是传string数据，今天看到CSDN上有人问如何传Struct。下面是我的解决方法。

[StructLayout(LayoutKind.Sequential)]
             public   struct  COPYDATASTRUCT
         {
            public int dwData;
            public int cbData;
            public int lpData;
        }
        [DllImport( " user32 " , EntryPoint  =   " SendMessageA " )]
         public   static   extern   int  SendMessage( int  Hwnd,  int  wMsg,  int  wParam,  ref  COPYDATASTRUCT lParam);
         const   int  WM_COPYDATA  =   0x004A ;

         // 定义要传递的Struct
        [StructLayout(LayoutKind.Sequential)]
         struct  WholeInfo
         {
            //SizeConst指定字符串很重要，后面要用到
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
            public string cPath;
            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]
            public string lPath;
            public bool status;
        }


// 发送方代码

            WholeInfo h = new  WholeInfo();
            h.lPath = " lPath " ;
            h.cPath  = " cPath " ;
            h.status = true ;
             int  size  =  Marshal.SizeOf( typeof (WholeInfo ));
             byte [] Bytes  =   new   byte [size];
             // 根据定义的尺寸分配内存块
            GCHandle GC  =  GCHandle.Alloc(Bytes, GCHandleType.Pinned);
            IntPtr ptr1  =  GC.AddrOfPinnedObject();
             // 获得Struct对应的IntPtr
            Marshal.StructureToPtr(h, ptr1, false  );            
            SendData.lpData  =  ptr1.ToInt32();
            SendData.cbData  = size;           

             int  intHWnd   =  FindWindow( null , @" 接收方 " );
             if  (intHWnd  >   0 )
             {
                SendMessage(intHWnd ,  WM_COPYDATA, 0,ref (SendData));
            }

// 接收方代码

         // 处理消息
         protected   override   void  DefWndProc( ref  System.Windows.Forms.Message m)
         {
            switch(m.Msg)
            {
                case WM_COPYDATA:
                    COPYDATASTRUCT RecvData = (COPYDATASTRUCT)m.GetLParam(typeof(COPYDATASTRUCT));
                     WholeInfo h = (WholeInfo)Marshal.PtrToStructure((IntPtr)RecvData.lpData, typeof(WholeInfo));
                    this.textBox1.Text = h.cPath ;
                    
                    break;
                default:
                    base.DefWndProc(ref m);
                    break;

            }

        }

关键的代码就是
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 10)]

这样C#才能分配正确的内存位置，但是要记住一个汉字占2位