9.4 Methods with a Result

In the beginning of this chapter, I mentioned you should never use class variables directly, outside a class. You’ve just learned how to alter a variable through a method with an argument, but what if you wanted to retrieve the value of the variable? The answer is simple. Use the method result:

 
class movingCircle { 
  Circle c; 
  Vec2 speed; 
 
5  void init(float r, Vec2 pos, Vec2 speed) { 
    c.r         = r    ; 
    c.pos       = pos  ; 
    this->speed = speed; 
  } 
10 
  float getRadius() { 
    return c.r; 
  } 
} 
15 
// somewhere in your application 
movingCircle mc; 
mc.init(0.1, p, Vec2(0.3, -0.5)); 
float radius = mc.getRadius();
 

At the end of this example, the float radius will have a value of 0.1. This is how you create a method with a result:

• Use the result type instead of the keyword void. In this case we want to retrieve a radius from the circle. A radius is a float, which means the result type will also be a float.
• The method contents should end with the keyword return, followed by the value that should be returned. This value will be passed to the caller.