How to Correctly Call Pointers to Member Functions in C ?

Calling Pointers to Member Functions in C

Pointers to member functions provide a convenient way to store and execute specific member functions while offering flexibility in dynamic binding. However, calling these function pointers has its unique syntax.

With non-static member functions, calling a function pointer requires providing both named parameters and a this pointer, which represents the object on which the function will be invoked. The following corrected code demonstrates the correct syntax:

typedef void (Box::*HitTest)(int x, int y, int w, int h);

for (std::list::<HitTest>::const_iterator i = hitTestList.begin(); i != hitTestList.end(); ++i)
{
    HitTest h = *i;
    (box->*h)(xPos, yPos, width, height);
}

Here, box is a pointer to the Box object that will function as the this pointer. By using box->*h, we are essentially calling the member function h on the specific Box instance pointed to by box.

Regarding adding member functions to the list, the corrected code would be:

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);
}

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