Pointers in c++ and runtime errors

Question

What is the issue with this code? It gives the output as expected, but there is a runtime error, and I don't know what it is.

Can somebody explain the concept behind it?

int main()
{
    int *a = new int(7);//assume the heap memory has address 4F
    int *p;
    p = a;
    cout << a << endl;
    cout << p << endl;
    cout << *a << endl;
    cout << *p << endl;
    *p = 10;
    cout << *a << endl;
    delete p;
    delete a;
    return 0;
}

Answer 1

You reassigned *p = 10 but a and p are still the same address in memory. As already mentioned, you are trying to delete the same memory space twice, which can explain the runtime error.

Answer 2

The error is due to the fact that a and p point to the same object, and so by doing

delete p;
delete a;

You are deleting 2 times the same object, and so the second time you are trying to delete memory that is already been freed