Dynamically allocating an array of objects

Question

I have a class that contains a dynamically allocated array, say

class A
{
    int* myArray;
    A()
    {
        myArray = 0;
    }
    A(int size)
    {
           


        

Answer 1

Using the placement feature of new operator, you can create the object in place and avoid copying:

placement (3) :void* operator new (std::size_t size, void* ptr) noexcept;

Simply returns ptr (no storage is allocated). Notice though that, if the function is called by a new-expression, the proper initialization will be performed (for class objects, this includes calling its default constructor).

I suggest the following:

A* arrayOfAs = new A[5]; //Allocate a block of memory for 5 objects
for (int i = 0; i < 5; ++i)
{
    //Do not allocate memory,
    //initialize an object in memory address provided by the pointer
    new (&arrayOfAs[i]) A(3);
}