是否允许指针作为有序STL容器中的键？ [英] Are pointers allowed as keys in ordered STL containers?

问题描述

有关这个问题要问如何比较指针应该如何解释的问题，请参阅C ++ Std。

There's this other question asking about how comparing pointers is supposed to be interpreted wrt the C++ Std.

所以我想知道C ++ Std在有序标准库（STL）容器中使用指针作为键是什么 - 即允许有

So I was wondering what the C++ Std has to say about using pointers as keys in ordered standard library (STL) containers -- i.e. is one allowed to have

std :: map< T1 *，T2>

到 std :: less 或内置操作符？

推荐答案

是的，因为它使用 std :: less ，这是必要的， code>< 不。 （< 将允许将来自不同序列的不同指针视为相等，这将导致 map etc，如果你插入来自不同序列的指针）。

Yes, because it uses std::less, which is required to result in a total order even if < doesn't. (< would be allowed to treat different pointers from distinct sequences as equal, which would result in an odd behaviour of map etc if you insert pointers from different sequences).

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