c# - 在 C# 中调用 C++ dll 方法

Question

我正在尝试在 C# 中调用 C++ DLL 方法，我之前已经成功调用了一些方法，但下面的方法总是失败，我对此一无所知：

C ++ 手册文档中的此描述：

方法头：

BOOL SxuptpEnumDevices ( 
    DWORD dwIpaddr,      /* Device server IP address*/  
    LPVOID lpbDevices,   /* Array address of the structure */  
    DWORD cbBuf,         /* Number of bytes of array */ 
    LPDWORD lpdwReaded,  /* Parameter address to which the number of byte copied will be returned */ 
    LPDWORD lpdwReturned /* Parameter address to which the number of structure copied will be returned */ );

方法说明：

dwIpaddr：指定将列出 USB 设备的设备服务器的 IP 地址。

lpbDevices : 指示 SXUSBDEVICE 结构数组的指针。它接收 USB 设备列表。

cbBuf：按字节指定 lpbDevices 指向的数组的大小。

lpdwReaded：表示复制到 lpbDevices 的字节数。

lpdwReturned：指示返回列出的 USB 设备数量的参数的指针。

*返回值：函数成功完成时返回TRUE，否则返回FALSE。

笔记：

typedef struct _SXUSBDEVICE { 
   char szPortName[32];   /* USB logical port name */
   char szDeviceName[64]; /* Device Name */
   DWORD dwIpPc;          /* IP address of connected PC */
   WORD wStatus;          /* Status information */
   WORD wVid;             /* Device VID */
   WORD wPid;             /* Device PID */
   char szLocation[16];   /* USB port info which the device is connected to */
   WORD wClass;           /* USB Interface Class */
} SXUSBDEVICE, *LPSXUSBDEVICE;

在 C++ 中调用：

BOOL result = SxuptpEnumDeviceServers(NULL, 0, &lpbDevices, (sizeof(SXPSERVER) * MAX_PSERVER), &dwReaded, &dwReturned);
if(result){
     //dwReturned = 1
     //lpbDevices[dwReturned - 1] will have value
} 

C＃

方法头

[DllImport(@"Sxuptp.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "SxuptpEnumDevices")]
public static extern bool SxuptpEnumDevices(
   uint dwIpaddr, 
   [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 0)] SXPSERVER[] lpbDevices,
   uint cbBuf,
   ref uint lpdwReaded,
   ref uint lpdwReturned);

笔记：

[StructLayout(LayoutKind.Sequential, Pack = 1, CharSet = CharSet.Ansi)]
    public struct SXUSBDEVICE
    {
        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
        public char[] szPortName; // USB logical port name

        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 64)]
        public char[] szDeviceName; // Device Name

        public uint dwIpPc; // IP address of connected PC
        public ushort wStatus; // Status information
        public ushort wVid; // Device VID
        public ushort wPid; // Device PID

        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 16)]
        public char[] szLocation; // USB port info which the device is connected to
        public ushort wClass; // USB Interface Class
    }

在我的项目中使用方法：

//Get all devices in USB Device Server from IP
int MAX_DEVICES = 64; 
uint dwIpaddr = (uint)IPAddress.NetworkToHostOrder((int)IPAddress.Parse("169.254.95.193").Address); 
SXUSBDEVICE[] lpbDevices = new SXUSBDEVICE[MAX_DEVICES]; 
uint lpdwReaded = 0, 
lpdwReturned = 0, 
cbuf = (uint)(Marshal.SizeOf(typeof(SXUSBDEVICE)) * MAX_DEVICES); 

if (Driver.Sxuptp.SxuptpEnumDevices(dwIpaddr, lpbDevices, cbuf, ref lpdwReaded, ref lpdwReturned))
{
     MessageBox.Show($"lpdwReaded: {lpdwReaded}, lpdwReturned: {lpdwReturned}");
}
else
{
     MessageBox.Show("Error");
}

这种方法总是返回 false，我认为某些 C# 代码在某处有一些错误，但我对此一无所知。请教我或提醒我任何东西来解决它！

标签： c#c++