delete[] an array of objects

Question

I have allocated and array of Objects

Objects *array = new Objects[N];

How should I delete this array? Just

delete[] array         


        

Answer 1

Not only is

delete [] array;

enough, but if you do

for(int i=0;i<N;i++)
    delete &array[i];
delete[] array;

you'll be causing undefined behavior, because

delete &array[i];

will be deleting things that weren't returned by a new operation.

Not to mention that the subsequent delete[] array; will call the destructor for all the objects that just had destructors called in the loop.

So don't do that.

Answer 2

Every use of new should be balanced by a delete, and every use of new[] should be balanced by delete[].

for(int i=0;i<N;i++)
    delete array[i];
delete[] array;

That would be appropriate only if you initialized the array as:

Objects **array = new Objects*[N];
for (int i = 0; i < N; i++) { 
    array[i] = new Object;
}

The fact that your original code gave you a compilation error is a strong hint that you're doing something wrong.

BTW, obligatory: avoid allocating arrays with new[]; use std::vector instead, and then its destructor will take care of cleanup for you. Additionally it will be exception-safe by not leaking memory if exceptions are thrown.

Answer 3

As a general rule you should delete/delete[] exactly those things that you allocated with new/new[]. In this case you have one allocation with new[], so you should use one call to delete[] to free that allocated thing again.

That the deletes in the for-loop won't compile is also a good indication that they are not the right way to do it.

Answer 4

Just delete[] array is sufficient. It is guaranteed that each element of the array is deleted when you delete an array using delete[] operator.

Answer 5

delete [] array

is enough.