I am trying to use a function pointer and I am getting this error:
cannot convert from void (__thiscall MyClass::*)(void)
to void (__cdecl *)(void)
// Header file - MyClass.h
class MyClass
{
public:
MyClass();
void funcTest();
protected:
void (*x)();
};
// Source file
#include "stdafx.h"
#include "MyClass.h"
MyClass::MyClass()
{
x = funcTest;
}
void MyClass::funcTest()
{
}
(Using: Visual Studio 6)
Can anyone notice anything that I've missed?
The type of non-static member-function is not void (*)()
. It is void (MyClass::*)()
, which means you need to declare x
as:
void (MyClass::*x)();
x = &MyClass::funcTest; //use fully qualified name, must use & also
You are trying to assign a member function pointer to a standalone function pointer. You can't use the two interchangeably, because member functions always implicitly have the this
pointer as their first parameter.
void (*x)();
declares a pointer to a standalone function, while funcTest()
is a member function of MyClass
.
You need to declare a member function pointer like this:
void (MyClass::*x)();
For more details see the C++ FAQ .
it's because a member function is different from a normal function, and hence the function pointers are different. Hence you need to tell the compiler that you want a MyClass function pointer, not a normal function pointer.youneed to declare x as: void (MyClass::*x)();
You declare a pointer to a function not taking any arguments and returning void. But you try to assign a member function pointer to it. You will need to the declare a pointer to a member function pointer and take its address like this: &MyClass::funcTest
The type of this pointer is void (MyClass::*)()
Have a look at the function pointer tutorials
Yes your type definition for x
is wrong. You need to defined it as a member function pointer as suggested by the compiler, ie, void(MyClass::*x)()
.
http://www.parashift.com/c++-faq-lite/pointers-to-members.html
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