Re: Still having problems with my member function pointers

Andrew Falanga wrote:

> Hi,
> 
>  About two weeks ago (or so) I posted here that I was having problems
> with getting a member function pointer to point to a member function
> without giving me grief.  I've gone to trying this on a trial program
> that I will post below in its entirety.  I just can't get it right and
> although I've tried the suggestions given to me from the other
> posting, I'm still doing something wrong.  So, here's my test program:
> 
> #include <iostream>
> 
> class base {
>    int somedata;
> 
>    public:
>    base();
> 
>    int GetData() {
>       return somedata;
>    }
> 
>    int (base::*ptrMemFunc)();
> 
> };
> 
> base::base() : somedata(5), ptrMemFunc(&base::GetData)
> {}
> 
> // this one's only in here to make sure I remembered how to use
> function pointers
> int AnInt() {
>    return 5;
> }
> 
> int main( ) {
>    base b;
>    int (*pAnInt)() = AnInt;
> 
>    std::cout << pAnInt() << std::endl;
> 
>    b.ptrMemFunc();

I think part of your trouble is that you have made the pointer-to-member
itself a member of the class. This results in a requirement to mention
the object twice:

  b.*(b.ptrMemFunc)();

Some other constellations with the pointer to member function are:

  base c;
  int (base::* local_ptr)() = &base::GetData;

  b.*(c.ptrMemFunc)(): /* call the pointer in c on the object b. */
  b.*local_ptr(); /* use a local pointer-to-member */

> 
> Thanks, and forgive my confusion.
> Andy

Bart v Ingen Schenau
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