C＃编组（C＃调用C ++ DLL） [英] C# marshalling (C# call C++ DLL)

问题描述

你能帮我解决一下这个问题吗？



我有一个C ++函数dll，它将由另一个C＃应用程序调用。

我需要的功能之一如下：

  unsigned   long  makeArray（ unsigned   char  * sendArr， unsigned   long  sendArrLen， unsigned   char  * recvArr， unsigned   long  * recvArrLen）;< pre> 

我尝试过：



我用C＃编写了以下代码：

 [DllImport（  test.dll，CallingConvention = CallingConvention.Cdecl）] 
  public   static   extern   ulong  makeArray（ byte  [] sendArr， ulong  sendArrLen， byte  [] recvArr， ulong  recvArrLen）; 
 
  private   byte  [] MakeArray（）
 {
  byte  [] arrSend =  new   byte  [] {0x00,0x12,0x34}; 
 
  ulong  nRecvArrLen =  0 ; 
  byte  [] arrRecv =  null ;  //  在c ++ dll函数中指定（可变大小） 
 
  if （makeArray（arrSend，（ ulong ）arrSend.Length，arrRecv，nRecvArrLen）==  1 ） //   System.AccessViolationException  
 {
  return  arrRecv; 
} 
 
  return   null ; 
} 

不幸的是，上面的代码无效......

（错误是System.AccessViolationException。而不是EntryPointNotFoundException）



我可以知道如何将指针传递给C ++函数？

如果不可能，是否有解决方法？



谢谢。

解决方案

它看起来很好，所以我认为问题出在dll中。我的第一个猜测是函数的导出不正确。



看看我的关于为C＃调用C ++的文章或者用好旧的 Dependency Walker <打开dll / A>

Could you guys please help me solve the following issue?

I have a C++ function dll, and it will be called by another C# application.
One of the functions I needed is as follow:

unsigned long makeArray(unsigned char* sendArr, unsigned long sendArrLen, unsigned char *recvArr, unsigned long *recvArrLen);<pre>

What I have tried:

I wrote the following code in C#:

[DllImport("test.dll", CallingConvention = CallingConvention.Cdecl)]
public static extern ulong makeArray(byte[] sendArr, ulong sendArrLen, byte[] recvArr, ulong recvArrLen);

private byte[] MakeArray()
{
    byte[] arrSend = new byte[] { 0x00, 0x12, 0x34 };

    ulong nRecvArrLen = 0;
    byte[] arrRecv = null; // assign in c++ dll function (variable size)

    if(makeArray(arrSend, (ulong)arrSend.Length, arrRecv, nRecvArrLen) == 1) //System.AccessViolationException
    {
        return arrRecv;
    }

    return null;
}

Unfortunately, the above code is not working...
(the error is "System.AccessViolationException". not "EntryPointNotFoundException")

May I know how can I pass a pointer-to-pointer to the C++ func?
If it is not possible, is there any workaround?

Thank you.

解决方案

It looks fine, so I think that the problem is in the dll. My first guess is that the export of the function is not correct.

Take a look at the code in my article about calling C++ for C# or open the dll with the good old Dependency Walker.

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