Why use getters and setters [duplicate]

Answer 1

To limit access to an internal state of an object.

Consider the classic example of a class of geometric shapes. Say, a Circle object. When you set the radius, you may want to automatically calculate the area (which would be a read-only property)

class Circle
{
     float radius;

    public float Radius
    {
        get { return radius; }
        set { radius = value;  area = Math.Pi * radius * radius;}
    }

    float area;
    float Area
    {
        get { return area;}
    }
}

If you allowed direct access to the "radius" data member, you could not update area when it changed. Further, if you allowed direct access to area, users could change it willy-nilly without regard for radius.