#399 – Overloading Unary Operators

You can overload any of the following unary operators: +, -, !, ~, ++, –, true, false.  A unary operator is an operator that can be applied to a single operand.

Overloading the negation (!) operator allows us to negate an instance of a class.

            Dog kirby = new Dog("Kirby", 13);

            Dog antiKirby = !kirby;

To overload the operator, we define a new method in our class that takes an instance of a Dog and “negates” it, returning a new instance.

        public static Dog operator !(Dog d1)
        {
            string notName = new string(d1.Name.Reverse().ToArray());

            return new Dog(notName, -1 * d1.Age);
        }

Below is an example of overloading the increment (++) operator.  (We really ought to overload the decrement operator as well).

            Dog olderKirby = kirby++;

        public static Dog operator ++(Dog d1)
        {
            return new Dog(d1.Name, d1.Age++);
        }