#409 – Example of Overloading the == Operator

Here’s a full example that shows how to overload the == operator for a reference type.

    public class PersonHeight
    {
        public int Feet { get; set; }
        public int Inches { get; set; }

        // Constructor goes here

        public override bool Equals(object obj)
        {
            return ((obj is PersonHeight) && ((PersonHeight)obj == this));
        }

        public override int GetHashCode()
        {
            return Feet.GetHashCode() ^ Inches.GetHashCode();
        }

        public static bool operator ==(PersonHeight ph1, PersonHeight ph2)
        {
            if (ReferenceEquals(ph1, ph2))
                return true;

            if (((object)ph1 == null) || ((object)ph2 == null))
                return false;

            return (ph1.Feet == ph2.Feet) && (ph1.Inches == ph2.Inches);
        }

        public static bool operator !=(PersonHeight ph1, PersonHeight ph2)
        {
            return !(ph1 == ph2);
        }

        // Also overload < and > operators
    }

Test cases:

            PersonHeight ph1 = new PersonHeight(5, 10);
            PersonHeight ph2 = new PersonHeight(5, 10);
            PersonHeight ph3 = null;

            bool check = ph1.Equals(null);
            check = ph1.Equals("NO!");
            check = ph1.Equals(ph2);
            check = PersonHeight.Equals(ph1, ph2);

            check = (ph1 == null);
            check = (ph3 == null);
            check = (ph1 == ph2);
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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

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