Kê khai và sụt lần Increment sử dụng C # cho phép bạn khai báo phiên bản của riêng bạn của thặng dư (+ +) và sụt lần (-) khai thác. Các quy tắc thông thường áp dụng khi tuyên bố các nhà điều hành, họ phải được công chúng, họ phải được tĩnh, và chúng phải được nguyên phân. | Declaring Increment and Decrement Operators C allows you to declare your own version of the increment and decrement operators. The usual rules apply when declaring these operators they must be public they must be static and they must be unary. Here is the increment operator for the Hour struct struct Hour . public static Hour operator Hour arg return arg . private int value The increment and decrement operators are unique in that they can be used in prefix and postfix forms. C cleverly uses the same single operator for both the prefix and postfix versions. The result of a postfix expression is the value of the operand before the expression takes place. In other words the compiler effectively converts this Hour now new Hour 9 Hour postfix now Into this Hour now new Hour 9 Hour postfix now now now pseudocode not valid C The result of a prefix expression is the return value of the operator. The C compiler effectively converts this Hour now new Hour 9 Hour prefix now Into this Hour now new Hour 9 now now pseudocode not valid C Hour prefix now This equivalence means that the return type of the increment and decrement operators must be the same as the parameter type. Operators in Structs and Classes It is important to realize that the implementation of the increment operator in the Hour struct works only because Hour is a struct. If you change Hour into a class but leave the implementation of its increment operator unchanged you will find that the postfix translation won t give the correct answer. If you remember that a class is a reference type and revisit the compiler translations explained previously you can see why this occurs Hour now new Hour 9 Hour postfix now now now pseudocode not valid C If Hour is a class the assignment statement postfix now makes the variable postfix refer to the same object as now. Updating now automatically updates postfix If Hour is a struct the assignment statement makes a copy of now in
