2 <clause number="8.7.6" title="Operators" informative="true">
3 <paragraph>An operator is a member that defines the meaning of an expression operator that can be applied to instances of the class. There are three kinds of operators that can be defined: unary operators, binary operators, and conversion operators. </paragraph>
4 <paragraph>The following example defines a Digit type that represents <keyword>decimal</keyword> digits-integral values between 0 and 9. <code_example><![CDATA[
9 public Digit(byte value) {
10 if (value < 0 || value > 9) throw new ArgumentException();
13 public Digit(int value): this((byte) value) {}
14 public static implicit operator byte(Digit d) {
17 public static explicit operator Digit(byte b) {
20 public static Digit operator+(Digit a, Digit b) {
21 return new Digit(a.value + b.value);
23 public static Digit operator-(Digit a, Digit b) {
24 return new Digit(a.value - b.value);
26 public static bool operator==(Digit a, Digit b) {
27 return a.value == b.value;
29 public static bool operator!=(Digit a, Digit b) {
30 return a.value != b.value;
32 public override bool Equals(object value) {
33 if (value == null) return false;
34 if (GetType() == value.GetType()) return this == (Digit)value;
36 public override int GetHashCode() {
37 return value.GetHashCode();
39 public override string ToString() {
40 return value.ToString();
50 bool equals = (a == b);
51 Console.WriteLine("{0} + {1} = {2}", a, b, plus);
52 Console.WriteLine("{0} - {1} = {2}", a, b, minus);
53 Console.WriteLine("{0} == {1} = {2}", a, b, equals);
56 ]]></code_example></paragraph>
57 <paragraph>The Digit type defines the following operators: <list><list_item> An implicit conversion operator from Digit to <keyword>byte</keyword>. </list_item><list_item> An explicit conversion operator from <keyword>byte</keyword> to Digit. </list_item><list_item> An addition operator that adds two Digit values and returns a Digit value. </list_item><list_item> A subtraction operator that subtracts one Digit value from another, and returns a Digit value. </list_item><list_item> The equality (==) and inequality (!=) operators, which compare two Digit values. </list_item></list></paragraph>