unary-operator

问题 What does the unary plus operator do? There are several definitions that I have found (here and here) but I still have no idea what it would be used for. It seems like it doesn\'t do anything but there has be a reason for it, right? 回答1: It's there to be overloaded if you feel the need; for all predefined types it's essentially a no-op. The practical uses of a no-op unary arithmetic operator are pretty limited, and tend to relate to the consequences of using a value in an arithmetic

问题 Java\'s unary plus operator appears to have come over from C, via C++. int result = +1; It appears to have the following effects: Unboxes its operand, if it\'s a wrapper object Promotes its operand to int , if it\'s not already an int or wider Complicates slightly the parsing of evil expressions containing large numbers of consecutive plus signs It seems to me that there are better/clearer ways to do all of these things. In this SO question, concerning the counterpart operator in C#, someone

问题 In JavaScript you can use ++ operator before ( pre-increment ) or after the variable name ( post-increment ). What, if any, are the differences between these ways of incrementing a variable? 回答1: Same as in other languages: ++x (pre-increment) means "increment the variable; the value of the expression is the final value" x++ (post-increment) means "remember the original value, then increment the variable; the value of the expression is the original value" Now when used as a standalone