how to call static member function as a parameter in dll

Question

2.33/5 (3 votes)

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header file

class MainClass
{

public:
    MainClass(void);
    ~MainClass(void);
public:
    void RegCallBack();
    static void __stdcall CB_CardEncode2(unsigned int nChannel,ISIL_ENCODE_DATA *pEncData,void *pContext);
};

Cpp file

extern "C"
{

void MainClass:: CB_CardEncode2(unsigned int nCh,ISIL_ENCODE_DATA *pEncData,void *pContext)
{
    ////////////FILEcreate/////////

    FILE *P=fopen("c:/Record/TP5.txt","w");
    fprintf(P, "i am card encode2!!!");
        fclose(P);
}

void RegCallBack()
{
    ISIL_Card_RegEncode2Callback(CB_CardEncode2,NULL);
}

Hi,
i am creating a dll,my problem is that i am passing as a parameter a static member function CB_CardEncode2 in ISIL_Card_RegEncode2Callback(CB_CardEncode2,NULL);
but CB_CardEncode2 member function is not calling.
i dont have idea how to pass a static member function as a parameter in other function and how to call CB_CardEncode2 static member function.

Thanks....

Hi,
I have to make entry point of the RegcallBack()
like
int __stdcall RegCallBack();

C#

__declspec(dllexport)  int __stdcall RegCallBack()
{
        ISIL_Card_RegEncode2Callback1(MainClass::CB_CardEncode2,NULL);
    //ISIL_Card_RegReadEncodeCallback(CB_CardReadEncode, NULL);
    return TRUE;

}

but when the compile then gives error,
please help me.give me any example.

Thanks

VB

when i am using classscope ISIL_Card_RegEncode2Callback1(MainClass::CB_CardEncode2,NULL);
then give this error
Error   1   error C2664: 'ISIL_Card_RegEncode2Callback1' : cannot convert parameter 1 from 'void (__stdcall *)(unsigned int,ISIL_ENCODE_DATA *,void *)' to 'CALL'   c:\documents and settings\administrator\desktop\test\dll_prj\dll_prj\test111\carddemo\mainclass.cpp 180 1   CardDemo

and when using
ISIL_Card_RegEncode2Callback1((CALL)MainClass::CB_CardEncode2,NULL);
then succesful
CB_CardEncode2 function not read.
where am i going wrong .please help me......

thanks

Posted 7-Feb-12 19:05pm

Tn1111

Updated 8-Feb-12 0:05am

v5

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Comments

Lakamraju Raghuram 8-Feb-12 1:21am

I do not think this will even compile, as you are not using class scope while calling CB_CardEncode2 method.
!!!!

2 solutions

Solution 1

I question is very vague and can't be trouble-shooted with the info provided. In general I am giving a code snippet for calling a class static function as a callback.

C++

#include <iostream>
using namespace std;

class MyClass
{
public:
   static int StaticFun(int i)
   {
      cout<<i<<endl;
      return 0;
   }
};

typedef int (*FN)(int);
void RegCallBack(FN pFn)
{
   pFn(100);
}

void main()
{
  RegCallBack(MyClass::StaticFun);
}

Hope this helps.

Posted 7-Feb-12 19:26pm

Lakamraju Raghuram

Updated 7-Feb-12 19:27pm

v2

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«_Superman_» · Accepted Answer · 2012-02-07T19:44:00

typedef void (__stdcall *CALLBACK)(int, void*);

void Global(CALLBACK pfn)
{
	pfn(10, 0);
}

class MainClass
{
public:
	void Reg();
	static void __stdcall Callback(int i, void* p);
};

void MainClass::Reg()
{
	Global(Callback);
}

void MainClass::Callback(int i, void* p)
{
	cout << i << " " << p << endl;
}

int _tmain(int argc, _TCHAR* argv[])
{
	MainClass m;
	m.Reg();

	return 0;
}