我们如何知道一个指针是用 new 还是 new[] 分配的？

Question

I'm trying to implement a unique_ptr class in C++, but how to know if the pointer we passed to it was allocated with new or new[] without using default_delete (my school standard doesn't allow c++11). I mean when you pass your pointer to the constructor like this for example:

unique_ptr<int> ptr(new int[10]);

how do you know inside of the class if you need to call delete[] or delete ?

Answer 1

You can't tell. And neither can std::unique_ptr .

Think about it. If it could be determined automatically, you wouldn't need two kinds of delete .

std::unique_ptr<int> ptr(new int[10]); is wrong, since it will try to call delete , rather than delete[] .