Friend functions a few questions

I read that to change access a private constant data member of a class you must declare your member function as constant.

(* The above should read*)
I read that to access a private constant data member of a class you must declare your member function as constant.

I think I also remember reading non-member friend functions of a class can not be declared as constant why is this?

To refresh my memory a little, constant data members must be initialized using a member initializer in the constructor definition correct. Suppose you want to initialize a private data member from a friend function would you use the same notation?

I read that to change access a private constant data member of a class you must declare your member function as constant.

You cannot change the access of a data member of a class.

I think I also remember reading non-member friend functions of a class can not be declared as constant why is this?

No non-member function can be declared const. When you declare a member function constant, it essentially ensures that *this is constant, and there is no this pointer for non-member functions.

To refresh my memory a little, constant data members must be initialized using a member initializer in the constructor definition correct. Suppose you want to initialize a private data member from a friend function would you use the same notation?

The best way to find out is to try it out yourself and then examine the results.