C# Language Specification - Willy .Net

C# LANGUAGE SPECIFICATIONE operator –(E x, U y);This operator is evaluated exactly as (E)((U)x – y). In other words, the operator subtracts a valuefrom the underlying type of the enumeration, yielding a value of the enumeration.• Delegate removal. Every delegate type implicitly provides the following predefined operator, where D isthe delegate type:D operator –(D x, D y);The binary - operator performs delegate removal when both operands are of some delegate type D. (Ifthe operands have different delegate types, a compile-time error occurs.) If the first operand is null, theresult of the operation is null. Otherwise, if the second operand is null, then the result of the operationis the value of the first operand. Otherwise, both operands represent invocation lists (§22.1) having oneor more entries, and the result is a new invocation list consisting of the first operand’s list with thesecond operand’s entries removed from it, provided the second operand’s list is a proper contiguoussubset of the first’s. (For determining subset equality, corresponding entries are compared as for thedelegate equality operator (§14.9.8).) Otherwise, the result is the value of the left operand. Neither of theoperands’ lists is changed in the process. If the second operand’s list matches multiple subsets ofcontiguous entries in the first operand’s list, the right-most matching subset of contiguous entries isremoved. If removal results in an empty list, the result is null. [Example: For example:end example]using System;delegate void D(int x);class Test{public static void M1(int i) { /* … */ }public static void M2(int i) { /* … */ }}class Demo{static void Main() {D cd1 = new D(Test.M1);D cd2 = new D(Test.M2);D cd3 = cd1 + cd2 + cd2 + cd1;cd3 -= cd1;// M1 + M2 + M2 + M1// => M1 + M2 + M2cd3 = cd1 + cd2 + cd2 + cd1; // M1 + M2 + M2 + M1cd3 -= cd1 + cd2;// => M2 + M1cd3 = cd1 + cd2 + cd2 + cd1; // M1 + M2 + M2 + M1cd3 -= cd2 + cd2;// => M1 + M1cd3 = cd1 + cd2 + cd2 + cd1;cd3 -= cd2 + cd1;// M1 + M2 + M2 + M1// => M1 + M2cd3 = cd1 + cd2 + cd2 + cd1; // M1 + M2 + M2 + M1}cd3 -= cd1 + cd1;// => M1 + M2 + M2 + M1}14.8 Shift operatorsThe > operators are used to perform bit shifting operations.shift-expression:additive-expressionshift-expression > additive-expressionFor an operation of the form x > count, binary operator overload resolution (§14.2.4) isapplied to select a specific operator implementation. The operands are converted to the parameter types ofthe selected operator, and the type of the result is the return type of the operator.162