为什么有些运营商喜欢::，。*，？ ：不能在C ++中重载？ [英] Why some operators like :: , .* , ? : can not be overloaded in C++ ?

问题描述

I understood the concept of overloading , but I am not clear why some operators can not be overloaded .I did not get any clear answer of it.

我尝试过：



我理解重载的概念，但我不清楚为什么有些运算符不能重载。我没有得到任何明确的答案。

What I have tried:

I understood the concept of overloading , but I am not clear why some operators can not be overloaded .I did not get any clear answer of it.

推荐答案

::无法重载，因为它是范围限定符（或名称解析）运算符 - 它指定了一个类和命名空间名称，并且它在类级别不可用，因为它有助于指定你指的是哪个班级。



同样，。并且*不能重载，因为它们指定访问权限，而不是操作本身。 Dot指定一个类的成员，而star是一个指针解析运算符。



？：不能被覆盖，因为它不是真正的运算符：它的语法if ... then ... else语句返回一个值。

:: can't be overloaded because it is the scope qualifier (or name resolution) operator - it specifies a class and namespace name and it's not available at a class level because it helps to specify which class you are referring to.

Similarly, "." and "*" can't be overloaded because they specify access, not an operation per se. Dot specifies a member of a class, and star is a pointer resolution operator.

?: can't be overridden because it isn't really an operator: it's syntactic sugar for an if...then...else statement that returns a value.

作为一般答案，对于这些运算符中的some，重载并不是完全不可想象的，但是Stroustrup和C ++委员会没有看到对他们有意义的使用，同时可能引入含糊不清或意外的副作用。



（就个人而言，我认为这是一种耻辱只有三元运算符，'？：'不能超载 - 我相信我能找到它的用途;-)）



见C++编程/运营商/运营商重载 - 维基教科书，为开放世界打开书籍 [ ^ ]和 Stroustrup： C ++样式和技术常见问题解答：为什么我不能超载... [ ^ ]

As a general answer, for "some" of these operators, overloading isn't entirely unthinkable, but Stroustrup and the C++ committee didn't see a meaningful use for them, while potentially introducing ambiguities or unexpected side effects.

(Personally, I think it's a shame that the only ternary operator, '?:' can't be overloaded - I'm sure I could find a use for that ;-) )

See C++ Programming/Operators/Operator Overloading - Wikibooks, open books for an open world[^] and Stroustrup: C++ Style and Technique FAQ: Why can't I overload ...[^]

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