Question

I have grouped several member functions into an array. How do I access a function from the array? I am getting ‘error C2064: term does not evaluate to a function taking 0 arguments.’ See below.

class A
{
public:

    //Constructor
    A()
    {
        //Fill function array
        ClipFunction[0] = &A::ClipTop;
        ClipFunction[1] = &A::ClipBottom;
        ClipFunction[2] = &A::ClipLeft;
        ClipFunction[3] = &A::ClipRight;
    }

    //Declare array
    typedef void (A::*ClipFunction_ptr) ();
    ClipFunction_ptr ClipFunction[4];

    //Clipping functions
    void ClipTop();
    void ClipBottom();
    void ClipLeft();
    void ClipRight();

    //Start clipping process
    void StartClip();

};

//Define clipping functions
void A::ClipTop() {}
void A::ClipBottom() {}
void A::ClipLeft() {}
void A::ClipRight() {}

//Define A::StartClip()
void A::StartClip()
{
    //Run through all functions in the array
    for (unsigned int i = 0; i < 4; i++)
    {
        ClipFunction[i](); //ERROR. How do I access ClipFunction[i] ???
    }

}   

Answer 1

I think the problem is that you need use “this” explicitly as in http://publib.boulder.ibm.com/infocenter/lnxpcomp/v8v101/topic/com.ibm.xlcpp8l.doc/language/ref/cplr034.htm .

So in your case, you should use

    (this ->* ClipFunction[i]) ();

instead of

    ClipFunction[i]();

PS

When I reply this post, I didn’t see Vite Falcon’s answer. Basically we are saying the same thing but I don’t think his code ” this->(*ClipFunction[i])()” will compile because GCC gives errors on my machine. “(this->*ClipFunction[i])()” is the correct form.