Question

I can’t figure out how this works, the code is really complicated because it is for a programming class I’m in. I can’t seem to get the program’s output when I work it through manually, it is the practice test for our final next week, I wouldn’t cheat on a test, the professor gave us the program and the output, I just don’t understand why that is the output..:

class FinalExam
{
private:

   int This;
   int That;

public:

   FinalExam(int, int);
   void One(int);
   int  Two(int);
};

FinalExam :: FinalExam(int A = 3, int B = 5)
{
   This = A;
   That = B;
}

void FinalExam :: One(int A)
{
   This --;
   That = A;
}

int FinalExam :: Two(int A) // Two gets the int 8
{
   int Scrap; 
   Scrap = This + That - A; // 5 + 2 - 8 = -1???? 
   return Scrap;
}

main()
{

   FinalExam Block;
   FinalExam Chunk(6, 7);

   Block.One(2);

   cout << Block.Two(3) 
        << '\n'
        << Chunk.Two(8); //I get lost on this 8, It should go to "Two"
}

And the output is:

1

5

I have looked at this for about an hour and I don’t understand.

Answer 1

FinalExam Block;  // Not passing any arguments to the constructor. In that case, 
                  // default argument values are taken. So, This = 3, That = 5


Block.One (2);     // This = 2; That = 2
                   // Because This is decremented and That is assigned the value
                   // passed to the method which is 2.


cout << Block.Two (3) ;  // 2 + 2 - 3 = 1 which is returned and is printed.

Similarly try the second one.