C＃包装类C ++的lib DLL [英] C# wrapper class for c++ lib dll

问题描述

我想C＃创建一个类来访问一个C ++ lib中的功能。在C ++函数的DLL：结果
布尔WriteReply（const的无符号字符*答复，const的无符号长reply_length）

。

的样本如何将其在C ++使用： -

 无符号短MSG_ID = 0×0000; 
字节msg_body [] = {（字节）（的GetTickCount（）/为0x100）}; //为回送数据
 
一个随机值//消息ID和消息体结合成一个大的味精
无符号长msg_length = sizeof的（MSG_ID）+的sizeof（msg_body）; 
字节* big_msg =新的字节[msg_length] 
 big_msg [0] = LOBYTE（MSG_ID）; 
 big_msg [1] = HIBYTE（MSG_ID）; 
的memcpy（（无效*）及big_msg [2]（无效*）msg_body，sizeof的（msg_body））; 
 
 //发送消息大
如果（！big_dev.WriteReply（big_msg，msg_length））
 {
 //做的东西在这里
 $} b $ b  

我似乎无法从C＃的功能传递给DLL（ AccessViolationException ）。这是我试过的命令： -

 字节[]字节组=新的字节[3] {0×01，0×02，×03 }; 
 IntPtr的unmanagedPointer = Marshal.AllocHGlobal（bytearray.Length）; 
 Marshal.Copy（字节数组，0，unmanagedPointer，bytearray.Length）; 
 
布尔writestatus =（布尔）NativeMethods.WriteReply（unmanagedPointer，（UINT）bytearray.Length）; 
  

和进口方面： -

 函数[DllImport（dllname.dll，入口点=WriteReply）] 
 [返回：的MarshalAs（UnmanagedType.U1）
内部静态外部布尔WriteReply（ IntPtr的味精，UINT reply_length）; 
  

请让我知道我在哪里出了错？谢谢！

< DIV CLASS =h2_lin>解决方案

我觉得最新的代码提供了一个线索，真正的问题：

 如果（！big_dev.WriteReply（big_msg，msg_length））
  

这可不行因为 WriteReply 是一个成员函数。你需要调用C风格的函数，而不是C ++成员函数。后者需要（代码示例中 big_dev ）的实例。

I am trying to create a class in c# to access the function in a c++ lib. The function in the c++ dll :
bool WriteReply(const unsigned char *reply, const unsigned long reply_length).

A sample of how its used in c++:-

unsigned short msg_id = 0x0000;                      
byte msg_body[] = {(byte)(GetTickCount()/0x100)};    // a random value for loopback data

    // combine the message id and message body into an big msg
    unsigned long msg_length = sizeof(msg_id)+sizeof(msg_body);
    byte* big_msg = new byte[msg_length];
    big_msg[0] = LOBYTE(msg_id);
    big_msg[1] = HIBYTE(msg_id);
    memcpy((void*)&big_msg[2], (void*)msg_body, sizeof(msg_body));

    // send the big message
    if (!big_dev.WriteReply(big_msg, msg_length))
    {
        //do something here
    }

I can't seem to pass the function from c# to the dll (AccessViolationException). This is the command i've tried:-

byte[] bytearray = new byte[3] { 0x01, 0x02, 0x03 };
IntPtr unmanagedPointer = Marshal.AllocHGlobal(bytearray.Length);
Marshal.Copy(bytearray, 0, unmanagedPointer, bytearray.Length);

bool writestatus = (bool)NativeMethods.WriteReply(unmanagedPointer, (uint)bytearray.Length);

and on the import side:-

[DllImport("dllname.dll", EntryPoint = "WriteReply")]
[return: MarshalAs(UnmanagedType.U1)]
internal static extern bool WriteReply(IntPtr msg, uint reply_length);

Please let me know where have i gone wrong?Thanks!

解决方案

I think the latest addition of code provides a clue as to the real problem:

if (!big_dev.WriteReply(big_msg, msg_length))

This cannot work because WriteReply is an member function. You need to be calling a C style function rather than a C++ member function. The latter requires an instance (big_dev in the code sample).

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