An Example to call MFC DLL using function pointer in C#.net

//An Example to call MFC DLL using function pointer in C#.net

1. Create new C#.Net windows application.
2. Copy the "MyDll.dll" to your project path, which we created in this post Click here.
3. Create two Textbox textBox1 and textBox2.

using System.Runtime.InteropServices; //Add this Line

namespace WindowsApplication1
{
public partial class Form1 : Form
{
private void button1_Click(object sender, EventArgs e)
{
//Add the Following Lines
IntPtr MyDll = LoadLibrary("MyDll.dll");
IntPtr procaddr = GetProcAddress(MyDll, "egAdd");
MyAdd mAdd = (MyAdd)Marshal.GetDelegateForFunctionPointer(procaddr, typeof(MyAdd));
int a = Convert.ToInt32(textBox1.Text);
int b = Convert.ToInt32(textBox2.Text);
int nRes = mAdd(a, b);
MessageBox.Show(nRes.ToString());
}
internal delegate int MyAdd(int a,int b);
[DllImport("kernel32.dll")]
internal static extern IntPtr LoadLibrary(String dllname);
[DllImport("kernel32.dll")]
internal static extern IntPtr GetProcAddress(IntPtr hModule, String procname);
}
}

C#.Net code to call MFC DLL

This is the code to call a function from vc++ DLL
(for example "MyDll.dll" which we created in this post click here )

1. Create a new C#.net windows application.
2. Copy the "MyDll.dll" to your project path, which we created in this post Click here.
3. Add this this following lines as below.
   

//using System.Runtime.InteropServices is used to call dll function in C#
using System.Runtime.InteropServices; //add this line

namespace WindowsApplication1
{
public partial class Form1 : Form
{

[DllImport("MyDll.dll", CharSet=CharSet.Auto)] //add this line
internal static extern Int32 egAdd(int a, int b); //add this line

public Form1()
{
InitializeComponent();
}

private void button1_Click(object sender, EventArgs e)
{
int nRes = egAdd(2, 4); //add this line
MessageBox.Show(nRes.ToString()); //add this line
}

}
}

How to create MFC DLL without wrapper class

Steps to create DLL

• Select File--> New
• Select Projects TAB and select MFC AppWizard(dll)
• Give Project Name as "MyDLL".
• Select "Regular DLL with MFC statically Linked" and click Finish.
• Select "Insert" Menu and choose "New Class".
• Select class type as "Generic Class"
• Give class name as "MyClass".
• Open "MyClass.h" in solution explorer window of File View tab.
• Paste the following code as in Figure 1.
• class CMyClass
  {
  public:
  __declspec(dllexport) CString Hello(CString csName);
  __declspec(dllexport) CMyClass();
  __declspec(dllexport) virtual ~CMyClass();
  
  };
• Open "MyClass.cpp" in solution explorer window of File View tab.
• Paste the following code as in Figure 2.
• CString CMyClass::Hello(CString csName)
  {
  
  csName="Hello"+csName;
  
  return csName;
  }
• Now compile and run the program.
• Now Make a copy "MyClass.h" from you project folder and Copy of "MyDLL.lib" and "MyDLL.dll" from debug folder to create a exe file.
  

Steps to create EXE apllcation

• Select File--> New
• Select Projects TAB and select MFC AppWizard(exe).
• Give Project Name as "MyEXE".
• Select "Dialog Based" and click Finish.
• paste "MyClass.h" from dll project folder to your exe Project folder.
• Paste "MyDLL.lib" and "MyDLL.dll" from debug of DLL project folder to exe project Folder.
• Open Project -->settings and select Link tab and type "Debug/MyDll.lib" in object/Library modules
  
• Open " File View" tab in solution explorer window.
• Right click on the project name and select add files to project.
• select "MyClass.h" and click ok.
• Now Open " Resource View" tab in solution explorer window and select Dialog and open "IDD_MYEXE_DIALOG".
• Now add a "Edit Box" to your dialog window and Right click on edit box and select "Class Wizard" .
• select "member variable" tab and select your edit box and click "Add variable " button.
• Give member variable name as "m_edName" and category as Control.
• Now click "ok" button and add the following code in "MyEXEDlg.cpp" as in Figure 3.
  
• #include "myclass.h" //at the top
• void CMyEXEDlg::OnOK()
  {
  CString csName;
  CString csResult;
  m_edName.GetWindowText(csName);
  CMyClass obj;
  csResult= obj.Hello(csName);
  AfxMessageBox(csResult);
  // CDialog::OnOK();
  }
  
• Now Run and execute program. and get result as in figure 4.