std :: set如何保持唯一，只有std :: less？ [英] How does std::set stay unique with only std::less?

问题描述

有没有人知道std :: set如何仅使用std :: less来防止重复？


我试过了几个STL实现并且

他们的代码非常难以理解（为了允许不同的编译器，我猜测b
。）

Does anyone know how std::set prevents duplicates using only std::less?

I''ve tried looking through a couple of the STL implementations and
their code is pretty unreadable (to allow for different compilers, I
guess).

推荐答案

Cory Nelson写道：

Cory Nelson wrote:

有没有人知道std :: set如何使用std :: less来防止重复？

.. 。

Does anyone know how std::set prevents duplicates using only std::less?
...

和？在您看来，这里到底出了什么问题？如果你有一个''less''

操作，那么可以通过它轻松定义相等如下：


''等于b''是当且仅当'小于b''或'b小于

a''为真时才是真的。


-

祝你好运，

Andrey Tarasevich

And? What exactly is the problem here, in your opinion? If you have a ''less''
operation, then equality can be easily defined through it as follows:

''a equals b'' is true if and only if neither ''a less than b'' nor ''b less than
a'' is true.

--
Best regards,
Andrey Tarasevich

On 2006-08-02 17:38:06 -0400，" Cory Nelson < ph ***** @ gmail.comsaid：

On 2006-08-02 17:38:06 -0400, "Cory Nelson" <ph*****@gmail.comsaid:

有没有人知道std :: set如何仅使用std :: less来防止重复？

Does anyone know how std::set prevents duplicates using only std::less?

它只是检查以确保每个元素都小于它之前的元素。

-

Clark S. Cox，III
cl*******@gmail.com

It just checks to make sure each element is less than the one it precedes.
--
Clark S. Cox, III
cl*******@gmail.com

Andrey Tarasevich写道：

Andrey Tarasevich wrote:

Cory Nelson写道：

Cory Nelson wrote:

有没有人知道std :: set如何使用std :: less来防止重复？

...

Does anyone know how std::set prevents duplicates using only std::less?
...

和？在您看来，这里到底出了什么问题？如果你有一个''less''

操作，那么可以通过它轻松定义相等如下：


''等于b''是当且仅当'小于b''或'b小于

a''为真时才为真。

And? What exactly is the problem here, in your opinion? If you have a ''less''
operation, then equality can be easily defined through it as follows:

''a equals b'' is true if and only if neither ''a less than b'' nor ''b less than
a'' is true.

什么？我只是希望它使用其他方式。那个

类型的比较可能是相当低效的，如果pred需要做很多工作。

And what? I was just hoping it used some other way than that. That
type of comparison might be rather inefficient if the pred needs to do
a lot of work.

-

祝你好运，

Andrey Tarasevich

--
Best regards,
Andrey Tarasevich

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