Class constructor with default parameters

Question

I the next simple constructor:

Vector(double x=0, double y=0) : x(x), y(y) {}

void operator+=(const Vector& other) {
    this->x += other.x;
    this->y += other.y;
}

But when I call it like this

Vector b();
Vector a(1,1);

and try to do a += b; compiler gives me a lot of errors saying that no operators exist. However when I do like this: Vector b(0,0); or Vector b(0); everything works(((

Why would you think that such a constructor would enable usage of +=? If you want the operator, you have to overload it. That has nothing to do with constructors. But as a side note, you should make this constructor explicit, or simple numbers will implicitly convert to vectors as x coordinates. — Sebastian Redl
– Sebastian Redl, Commented Sep 23, 2014 at 13:54
@RobertMutke I do like to use this in such cases to be clear which of the two objects is being used. — Neil Kirk
– Neil Kirk, Commented Sep 23, 2014 at 14:02
@NeilKirk kinda matter of taste, but still should be rather avoided stackoverflow.com/questions/2337540/… — Robert Mutke
– Robert Mutke, Commented Sep 23, 2014 at 14:09

Luchian Grigore · Accepted Answer · 2014-09-23 13:56:56Z

3

Vector b(); doesn't create an object. It declares a function.

Vector b;
Vector a(1,1);

should work.

answered Sep 23, 2014 at 13:56

Luchian Grigore

260k68 gold badges465 silver badges634 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Class constructor with default parameters

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related