Does delete delete every element in a vector and free the memory?-CodePudding

    vector<int>* v = new vector<int>;
    for (int i = 0; i < 100; i  ) {
        (*v).push_back(i);
    }
    delete v;

Do I delete every element of the vector and free the memory? If not how do I free the memory?

CodePudding user response：

An allocating new expression allocates memory, constructs a dynamic object into that memory, and returns a pointer to that object. When you pass such pointer to delete, the pointed object is destroyed and the memory is deallocated.

When an instance of a class, such as a vector is destroyed, its destructor is called. The destructor of vector destroys all elements of the vector.

Sidenote 1: It's rarely useful to use allocating new and delete. When you need dynamic storage, prefer to use RAII constructs such as containers and smart pointers instead.

Sidenote 2: You should avoid unnecessary use of dynamic memory in general. It's quite rare to need singular dynamic vector such as in your example. I recommend following instead:

std::vector<int> v(100);
std::ranges::iota(v, 0);

Sidenote 3: Avoid using (*v).push_back. It's hard to read. Prefer using the indirecting member access operator aka the arrow operator instead: v->push_back