How to Correctly Call and Add C Pointers to Member Functions?

Calling C Pointer to Member Functions

Understanding the proper syntax for invoking pointers to member functions in C is crucial. This question explores the specific method for calling such pointers, as well as the process of adding member functions to a list.

Calling Pointers to Member Functions

The question showcases a code snippet attempting to invoke pointers to member functions using the syntax:

(*h)(xPos, yPos, width, height);

However, the correct syntax requires providing both the named parameters and the this pointer. Therefore, the corrected line becomes:

(box->*h)(xPos, yPos, width, height);

This ensures that the correct this pointer is used when calling the member function.

Adding Member Functions to a List

The question also demonstrates how to add member functions to a list. Here, pointers to member functions are being stored in a std::list. The code below illustrates the process:

std::list<HitTest> list;

for (std::list<Box*>::const_iterator i = boxList.begin(); i != boxList.end(); ++i)
{
    Box * box = *i;
    list.push_back(&box->HitTest);
}

This code iterates through a list of Box pointers and pushes the address of each HitTest member function onto the std::list. Each member function is represented by a pointer to member function that references the this pointer of the specific Box object.

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