class

[DarkParadox]

For number 1 and 2 :

class Rectangle {
    int width, height;
  public:
    Rectangle ();
    Rectangle (int,int);
    int area (void) {return (width*height);}
};

1.In line 6, there is int area (void) ....
So, the question is what is the function of having void inside int area?
What is the difference with int area () {return (width*height);}

2.Is there any difference between {return w*h;} and {return (w*h);}
If yes please explain it...

For number 3 :

Rectangle rectb;   // ok, default constructor called
Rectangle rectc(); // oops, default constructor NOT called  

3. what is default constructor?
Thx

[TheIdeasMan]

Hi,

1. No difference, it just means the function does not accept arguments. It has never been a requirement for C++ to specify void there, but it was in C.

2. No difference. Parentheses are extraneous there.

3. The constructor that takes no arguments.

The problem with this part:

Rectangle rectc(); // <--- a function declaration named rectc, which returns a Rectangle type