Is it necessary to call delete[] vs delete for char arrays?

Question

I'm utilizing a library written by a collegue and discovered that valgrind was spewing out errors related to the delete.

The problem was that there were allocations of char arrays like

char* s = new char[n];

followed up later with delete s

instead of delete[] s

He tells me that the difference is really that delete[] s will call a destructor for the object at each position in s (if it has one), in this case it doesn't because it's a primitive type. I believe that is true.

So delete s is not really a bug as such and valgrind is just being very thorough.

Will it still definitely free all the memory associated with s?

Answer 1

If you allocate an array using new[], you have to destroy it using delete[]. In general, the functions operator delete(void*) and operator delete[](void*) aren't guaranteed to be the same.

Refer here

Answer 2

Forget about destructors. The difference between new/delete and new[]/delete[] is that these are two completely unrelated, independent memory allocation mechanisms. They cannot be mixed. Using delete to deallocate memory allocated with new[] is no different than using free for the same purpose.

Answer 3

The standard says nothing about how the memory will get deleted -- it merely says that to not match the correct new with the correct delete is undefined behavior.

Actually, new[] followed by delete usually frees all the memory that was allocated with new[], but destructors for the items in that array are not called correctly. (Most of the time -- not that the standard mandates that)

Rather than dynamically allocated arrays, you should consider use of vector.