C语言中的回调方法 [英] Call back method in C

问题描述

我正在尝试从C dll文件调用一个C#函数，我的需要是在我的C dll文件知道的特定时间段内在我的C#应用​​程序中调用一个函数.

为此，我创建了一个示例代码对其进行测试，但是它对我不起作用.

任何人对此都有任何想法，请纠正我
我的示例代码在下面给出

C dll代码

I am trying to call one C# function from C dll file, My need is to invoke one function in my c# application in a particular time period that my C dll file knows

for that I create one sample code for testing it, But its not working to me.

any one have any idea about this please correct me
My sample code is given below

C dll code

extern "C"
{
	
	void (*foo1)(int)= NULL;
  __declspec(dllexport) void DisplayHelloFromDLL()
  {
	
	   //foo = &my_int_func;
	  foo1(2);
    printf ("Hello from DLL !\n");
	

  }

   __declspec(dllexport) void InitializeFun(void (*foo)(int)) 
  {
	  foo1=foo;
	}

 

}

C#控制台应用程序

C# console application

public class NativeMethods
   {
       private const string KERNEL32_DLL = "Kernel32.dll";
       [DllImport(KERNEL32_DLL)]
       static internal extern IntPtr LoadLibrary(string szFileName);
       [DllImport(KERNEL32_DLL)]
       static internal extern IntPtr GetProcAddress(IntPtr hLibrary, string szProcName);
       [DllImport(KERNEL32_DLL)]
       static internal extern int FreeLibrary(IntPtr hLibrary);
   }


   class Program
   {
       [DllImport("TestLib.dll")]
       public static extern void DisplayHelloFromDLL();

       [DllImport("TestLib.dll")]
       public static extern void InitializeFun(VoidDelegate MyFunc);

       public delegate void VoidDelegate();


       static void Main(string[] args)
       {
           Console.WriteLine("This is C# program");

           IntPtr hUser32 = NativeMethods.LoadLibrary("TestLib.dll");
           IntPtr pMethod = NativeMethods.GetProcAddress(hUser32, "InitializeFun");



           VoidDelegate method2 = (VoidDelegate)Marshal.GetDelegateForFunctionPointer(pMethod, typeof(VoidDelegate));
           InitializeFun(method2);

           DisplayHelloFromDLL();
           string str = Console.ReadLine();


       }

       public static void MyFunc()
       {
           Console.WriteLine("I was called by c dll ...");
       }
   }

推荐答案

VoidDelegate method2 = (VoidDelegate)Marshal.GetDelegateForFunctionPointer(pMethod, typeof(VoidDelegate));

你为什么做这个?当然，您只想要

Why are you doing this? Surely you just want

VoidDelegate method2 = MyFunc;

实际上，您可能只能够做到

Actually you might well just be able to do

InitializeFun(MyFunc)

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