Re: [Dev-C++] Newbie question Classes/Objects/Accessors????

[Per W. <pw...@ia...>]

If a class have a requirement that two values must always be in sync, the
'setter' method may then automatically adjust the two values on change.
Since it isn't possible to just write-protect a value, the class must then
also have a 'getter' method.

class Pythagoras {
protected:
    double a,b,c,area;
    Pythagoras() {
        a = b = c = area = 0;
    }
    void SetA(double v) {
        a = v;
        Evaluate();
    }
    void SetB(double v) {
        b = v;
        Evaluate();
    }
    double GetA() const {
        return a;
    }
    double GetB() const {
        return b;
    }
    double GetHyp() const {
        return c;
    }
    double GetArea() const {
        return area;
    }
protected:
    void Evaluate() {
        c = sqrt(a*a + b*b);
        area = a*b/2;
    }
};

With the above class, it is impossible for a user to mess up the triangle
area without doing stupid low-level tricks with pointers etc.

/Per W

On Tue, 20 May 2003 Rus...@ao... wrote:

> I understand the basics of Classes, but what determines which
> members/functions should be public/private?
>  The Accessor functions (is that the correct terminology?) seem to take a
> public member of a class and attach some argument/value/data to a private member
> of the same class. What is the logic behind this? I can understand what is
> being done, but I don't understand the reasoning.
>
>
> Regards,
> Russ
>
>
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