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Tham khảo tài liệu 'praise for c# 2.0: practical guide for programmers 2005 phần 5', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 5.2 Assignment Operators 85 The destination Variable and the source Expression must be type compatible. The Variable can store either a simple data value or an object reference. Assignments of Simple Values Examples int a b c a 1 b a a c 1 a OK. OK. Error Variable must be initialized before used. Error Destination must be a variable. c a b OK. a b c Error Destination must be a variable. The assignment operator has the lowest precedence allowing the expression on the righthand side to be evaluated before any assignment int a a 1 System.Console.WriteLine a a a - 1 - has higher precedence than System.Console.WriteLine a a 2 a 3 2 0 3 System.Console.WriteLine a Output 1 0 2 Assignments of References Examples Id id1 new Id Frank 1 Id id2 new Id Emma 2 id2 id1 Copying references by assignment does not copy the content of the source object only its reference. Now id2 refers to the same Id object as id1 and the previous object Id Emma 2 is eligible for garbage collection. 86 Chapter 5 Operators Assignments and Expressions 5.2.2 Multiple Assignments An assignment always returns the value of the expression on the right-hand side as a result. Therefore initializing several variables to a common value or reference using multiple assignment statements int a b c a 1 b 1 c 1 can be reduced to a single statement using multiple assignments as shown a b c 1 a b c 1 The preceding example illustrates the importance of right associativity for the assignment operator. 5.3 Conditional Operator The conditional operator evaluates a boolean expression and depending on its I EBNF I resultant value either true or false executes one of two expressions as defined here ConditionalOperator Condition ExprIfConditionTrue ExprIfConditionFalse. The conditional operator therefore is equivalent to a simple if-else statement if Condition ExprIfConditionTrue else ExprIfConditionFalse For example minimum a b a b is equivalent to if a b minimum a else minimum b Another example absolute a 0 -a a 5.4 Null .
