How to determine if a buffer is freed or not

问题

I use new to allocate a buffer, as follows:

    BYTE *p;

    p = new BYTE[20];


    ...

    delete p;

After p is deleted, if I do NOT assign NULL to p, is there a way to determine whether it has already been freed?

回答1:

You cannot determine that, and that's one of the main reasons you usually rely on higher-level mechanisms to handle memory, such as smart pointers (shared_ptr, unique_ptr and so on), or in your case rather std::vector, to deal with raw memory in a way that guarantee no double delete, forgotten delete, or other nasty mistakes that launch your program in undefined behavior land.

来源：https://stackoverflow.com/questions/27374640/how-to-determine-if-a-buffer-is-freed-or-not