Question

I got really stuck trying to deallocate memory using delete without it being in a for loop.

    MyClass *Array[10];

cout << "Step 1 - Allocation" << endl << endl;
Array[0] = new MyClass();
Array[1] = new MyClass();
Array[2] = new MyClass(2, 4.6);
Array[3] = new MyClass(*Array[2]);
Array[4] = new MyClass();
Array[5] = new MyClass(13, 66.6);
Array[6] = new MyClass(75, 9.43);
Array[7] = new MyClass(*Array[6]);
Array[8] = new MyClass(*Array[1]);
Array[9] = new MyClass(*Array[3]);

cout << endl << "Step 2 - Write" << endl << endl;
for(int i=0; i<10; i++)
{
    Array[i]->write();
    cout << endl;
}

cout << endl << "Step 3 - Deallocation" << endl << endl;

I tried delete[] Array, but it doesn’t work.

The code must stay as it is as it’s correct by what is asked to do. The only thing is to add a delete (single-lined and not a for loop) to delete Array.

Answer 1

You need to delete each object that you’ve created using new:

for (unsigned i(0); i < 10; ++i)
    delete Array[i];

Array itself is a local variable; you did not use new to create it, so you do not use delete to destroy it. It will be destroyed when it goes out of scope.

To address the updated constraint that the deletion must be done “single-lined and not a for loop,” one could, I suppose, write:

delete Array[0]; delete Array[1]; delete Array[2]; delete Array[3]; delete Array[4]; delete Array[5]; delete Array[6]; delete Array[7]; delete Array[8]; delete Array[9];

This is a single line of code and uses no loops. It is not possible to use a single delete expression to destroy what are ten effectively unrelated objects.

---

But do not do this. Really. Manual resource management is dangerous and very difficult to do correctly. C++ has automatic resource management capabilities and you should use them. In this case, it would be far better to use a std::vector<MyClass>:

std::vector<MyClass> Array;
Array.push_back(MyClass());
Array.push_back(MyClass());
Array.push_back(MyClass(2, 4.6));
Array.push_back(MyClass(Array[2]));
// Etc.

There’s no new in this example, thus no delete is required. The std::vector will clean everything up when it is destroyed.