Encapsulation

There are a lot of questions here and rightly so because these are all new concepts. You will gain better understanding as you move forward with Objective-C.

Q. And maybe give another small example of encapsulation?

Encapsulation in plain english means hiding direct access to data and only providing access via functions or methods.

Q. Why does the instructor mention declaring two functions? I can only see one – 'makeSphere'

I think that was an error. Sorry about that.

Q. What is actually happening during the implementation and calling of the function? The instructor keeps mentioning 'passing' but this process is opaque to me.

In the main function when you call the makeSphere you are giving it two variables: Sphere ball = makeSphere(c, r); You are passing values to that function which can be accessed within the function using the parameter names in its implementation. That's what he means by 'passing'.

Q. In the function call, how come you don't need a star notation?

It all depends what is being returned by the function. In this case the function returns a struct and the struct is simply a container of values. You don't have pointer to a struct.

Q. Also, in the first part of the lesson (structs) the instructor uses the values 24, 32, 45 and 67. These change in the second part of the lesson (structs + functions) – is this intentional? Is changing them meant to demonstrate something?

No that was just part of the editing where we might have had to correct some mistake while recording.

Q. At the end the instructor mentions making multiple spheres using the makeSphere function – how would you do this? I can't see how combining a struct with a function has saved time here or has the potential to save time.

You would just call the function to make sphere each time.

int main()
{
    float c[] = {23, 45, 67};
    float r = 32;
    Sphere ball = makeSphere(c, r);

   Sphere ball2 = makeSphere(c,45); // you don't have to store values in a variable to pass it to a function

    float c2[] = {33, 25, 17};
    float r2 = 77;
   Sphere ball3 = makeSphere(c2,r2);

    printf("center %f %f %f radius %f\n", ball.center[0], ball.center[1], ball.center[2], ball.radius);

    return 0;
}