为什么++ x是左值而x ++是右值？ [英] Why is ++x a lvalue and x++ a rvalue?

问题描述

所以我一直在阅读左值和右值，对于 ++ x 和 x ++ 进行此分类。

So I've been reading up on lvalue and rvalues and I'm a bit confused about the difference between ++x and x++ when it comes to this categorization.

为什么 ++ x 是左值，而 x ++ 一个右值？

Why is ++x a lvalue and x++ a rvalue?

推荐答案

++ x 返回对该对象的引用您增加了，其中 x ++ 返回 x 的旧值的临时副本。

++x returns a reference to the object you incremented, where as x++ returns a temporary copy of x's old value.

至少这是按惯例实现这些运算符的正常方式。并且所有内置类型都以这种方式工作。而且，如果您已经了解了左值/右值，那么您会发现，由于前缀运算符本身返回命名对象，因此它将是左值，而后缀运算符将返回本地临时副本，然后该副本将作为右值

At least this would be the "normal" way by to implement these operators by convention. And all built-in types work this way. And if you've read about lvalues / rvalues then you would see that since the prefix operator returns the named object itself it would be an lvalue, where as the postfix operator returns a copy of a local temporary, which would then qualify as an rvalue.

注意：另外，我们现在有prvalues，xvalues等，因此这些天在技术上要复杂一些。请在此处获取更多信息。

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