How do you invoke something like this from C/C++ etc:

Implementation:

```
int foo(int a, int b)
{
    a += b;
    return a;
}

```

Call: 

```
int newNumber = foo(1,2);

```

I think know this part:

Implementation:

```
-(int) foo: (int)a addTo: (int)b
{
    a += b;
    return a;
}

```

Call: ???

But how do you call this method in another method of the same class and retrieve that a?

I apologize in advance is this is blatantly in documentation or in another question - guess I need a little extra help. : /