How to convert C++ class as C# object?

Question

 

I am trying to use a class from C++ code as an object.

How can I convert the C++ class to an object so that they can be accessed when I convert them to dll in C#.

For Example:

 

class extClass()

{

public:

private:

int myFun1();
int myFun2();
char m_strSNO[20];
char m_strRegCode[20];

}

How can I make the class as objects to be called in C# If I use a DLL linkage?

 

using System;<br/>
using System.Linq;<br/>
using System.Collections.Generic;<br/>
using System.Windows.Forms;<br/>
<br/>
namespace TestSDKCS<br/>
{<br/>
  static class Program<br/>
  {<br/>
    /// <summary><br/>
    /// The main entry point for the application.<br/>
    /// </summary><br/>
    [MTAThread]<br/>
    static void Main()<br/>
    {<br/>
      Application.Run(new Form1());<br/>
<br/>
      <strong> extDevice d = new extdevice();<br/>
      <br/>
      Textbox1.Text = d.mstrSNO.ToString();<br/>
</strong>
<br/>
<br/>
    }<br/>
  }<br/>
}

 

I am currently using DLLExport classes to import the functions

but during runtime the myFun1 and myFun2 gives unHandledException error.

please help to get myFun1 and myFun2  executed.

---

Sri Hari Haran Seenivasan

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Answer 1

Hi Hari,

You will need to use bridging functions to attain this functionality.

 

eg. C++

class MyTestClass
{
 public:
  MyTestClass();
  ~MyTestClass();

  int MyMethod(int value);
}

You will then need to create bridging functions to access the class and functions.

eg. C++

/*
 Instantiate my object
*/
extern "C" MyTestClass* CreateMyTestClass()
{
  return new MyTestClass();
}

/*
Dispose of my object
*/
extern "C" void DisposeMyTestClass(MyTestClass* object)
{
  if(object != NULL)
  {
    delete object;
    object = NULL;
  }
}

/*
Call my class function
*/
extern "C" int CallMyTestClassMethod(MyTestClass* object, int value)
{
  if(object != NULL)
  {
    return object->MyMethod(value);
  }
}

Once that is done you can use p/invoke in c# to construct, call and dispose of your unmanaged class

eg. C#

[DllImport("MyTest.dll")]
static public extern IntPtr CreateMyTestClass();

[DllImport("MyTest.dll")]
static public extern void DisposeMyTestClass(IntPtr object);

[DllImport("MyTest.dll")]
static public extern int CallMyMethod(IntPtr object, int nValue);

You can then call these methods as required from c# code

Hope this helps. (Code for example only)

Answer 2

Is the same with .lib libraries?

Answer 3

Hello, I have been reading on internet and is not posible to use .lib directly in C#. First I have to make a .dll using methods like dhTodays answer.