there's many ways to implement private data. if you prefer non member functions, a class is a bunch of extra keystrokes to achieve the same as the old fashioned C private data.
if you prefer non member functions to member functions, your private data becomes a global variable or struct in a file, and the private data is not accessible by getter/setter functions that are externalised.
Unless you're a fan of `friend` keyword ;)
however, it requires less keystrokes to implement private data in C, than it does to create a class to store private data.
therefore it's questionable, if you are preferring non member non friend functions, whether you should use classes when you want private data.
i refute the idea that private data is a reason to use classes, if you are preferring non member non friend functions as advocated by Stroustrup, Meyers and Stepanov.
as i said already
> There's very little reason for class members unless you want inheritance or polymorphism.