Question

Looking for some help with arrays and pointers and explanation of what I am trying to do.
I want to create a new array on the heap of type Foo* so that I may later assign objects that have been created else where to this array. I am having troubles understanding what I am creating exactly when I do something like the following.

Foo *(*f) = new Foo*[10];

Also once I have created my array how do I access each element for example.

(f + 9)->fooMember(); ??????

Thanks in advance.

Answer 1

Foo *(*f) = new Foo*[10];

The parentheses in the declaration are unnecessary, so this is the same as:

Foo **f = new Foo*[10];

In any case, the new Foo*[10] allocates space for ten Foo*s and leaves them uninitialized. It returns a pointer to the initial Foo* in the array (the zeroth element), which you assign to f.

To access elements of the array, you simply use subscripting:

f[0] = new Foo;
f[0]->fooMember();

Remember that anything you create using new[] must be freed once when you are done with it by calling delete[] on the pointer. For example:

delete[] f;

This does not delete the elements pointed to by the Foo*s in the array. If you create Foo objects using new, you must delete them before you delete the array. For example, to free the element we created above:

delete f[0];