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如何实现类的成员函数创建线程

2012-03-16 12:24 453 查看
class CMySocket
{
  public:
  DWORD WINAPI WorkThread(LPVOID CompletetionPortID);
  ...
};


  有如上类,在类中某函数想以函数(WorkThread)
  CreateThread(NULL, 0, WorkThread, ¶m, 0, &ThreadID))
  编译会报错:cannot convert parameter 3 from 'unsigned long (void *)' to 'unsigned long (__stdcall *)(void *)' None of the functions with this name in scope match the target type
  

解决方法:
  1.
  这种情况,一般是将线程函数申明为静态,如:

class CRealtimeTask
{
  public:
  static UINT taskmain(LPVOID param);
  BOOL StartTask();
};


  在类中定义的成员函数,VC在编译时会强加一个this指针,所以才会出现上边的情况.将该成员函数声明为static类型,可以将this指针除去,但static成员函数只能访问static成员.
  

2.
  以将线程函数申明成友员函数,这样可以传入该类的指针,访问类的成员; 

class CRealtimeTask
{
  public:
  friend UINT taskmain(LPVOID param);
  BOOL StartTask();
};

UINT taskmain(LPVOID param)
{
  CRealtimeTask * pTaskMain = (CRealtimeTask *) param;
  //通过pTaskMain指针引用.
  return TRUE;
}

BOOL CRealtimeTask::StartTask()
{
  AfxBeginThread(taskmain,this);
}


  3.
  可以对成员函数实现回调,并访问非静态成员的,如下所示,这是为了实现线程函数访问类成员而实现的类.比MFC的实现方法好象要好一点.
class base;
typedef int (base::*fnCallBack)(void *p);
struct callback(void *param;fnCallBack *pfuc;base *pThis;};

class base
{
  static int myThreadfuc(void *p)
{
  	struct callback *p1=(struct callback *)p;

  	base *pthis=p1->base;
fnCallBack *pfuc=p1->pfuc;void *param=p1->param;

  	int i=(pthis->*pfuc)(param);
delete p;

  	return i;
  }

  public:

  void myCreateThread(fnCallBack pfuc,void *param)
{
  	struct callback *p=new struct callback;

  	p.param=param;
p.pThis=this;
p.pfuc=pfuc;

  	::CreateThread(myThreadfuc,p);
  }

  virtual int myCallBack(void *p)
{
printf("It's base class./n");
return 0;
}

};

class derived: public base
{
  int myCallBack(void *p){printf("It's derived class/n");}
};

void myCreateThreadImitate(fnCallBack fuc,void *p)
{
  (*fuc)(p);
}

void main()
{
  base p;char *param;
  p.myCreateThread(&(base::myCallBack),param);
  derived p2;p2.myCreateThread(&(base::myCallBack),param);
}
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