Here’s a full example that shows how to overload the == operator for a reference type.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
| 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:
1
2
3
4
5
6
7
8
9
10
11
12
| 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); |