Why Can We Delete a Pointer to a Constant Object?

Deleting a Pointer to Constant (T const*)

One may wonder why one is allowed to call the non-const destructor of a class through a const pointer. After all, const pointers are meant to prevent modifications to the underlying objects. However, deleting a const pointer to an object does not modify the object itself.

The primary reason for allowing the deletion of a const pointer is to support the deletion of const objects. Here's an example:

<code class="cpp">const Foo *f = new Foo; // dynamically create object that cannot be changed</code>

In this scenario, the object pointed to by f is created dynamically and cannot be modified because it is a const object. However, the const pointer allows us to access the const member functions of the object. When we are finished with the object, we need to delete it:

<code class="cpp">delete f; // delete it</code>

Without the ability to delete a const pointer, we would not be able to use const objects dynamically created in such a manner.

It's important to note that this rule applies not only to dynamically created const objects but also to const objects allocated on the stack:

<code class="cpp">{
 const Foo f; // const object on the stack
 // use it
} // destructor called here</code>

If destructors could not be called on const objects, we could not use const objects at all. This ability provides the necessary flexibility to manage const objects effectively in C .

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