How to detect if a pointer was deleted and securely delete it?

Question

In C++ How to decide or know if a pointer was deleted before??

when i tried to delete a pointer that was previously deleted in another part of the c

Answer 1

Smart pointer are better choice to avoid such problems (but you must have complete understanding before using them also), but I would like to mention performance limitations associated with Smart pointers, reason is they usually use atomic operations for example InterlockedIncrement in Win32 API for reference counting. These functions are significantly slower than plain integer arithmetic. I am not sure such little performance penalty acceptable in your case or not.

What i usually do is (so i don't have to spend days later on to debug nasty bugs), i spend lot of time on design, and object lifetime, before moving for actual coding, as i delete memory I specifically set pointer to NULL, it is good practice as far as i think. Again perhaps the real solution is to spend more time on determining dependencies and object life time before moving on!