C++, array of objects without

Question

I want to create in C++ an array of Objects without using STL.

How can I do this?

How could I create array of Object2, which has no argumentless constructor

Answer 1

If the type in question has an no arguments constructor, use new[]:

Object2* newArray = new Object2[numberOfObjects];

don't forget to call delete[] when you no longer need the array:

delete[] newArray;

If it doesn't have such a constructor use operator new to allocate memory, then call constructors in-place:

//do for each object
::new( addressOfObject ) Object2( parameters );

Again, don't forget to deallocate the array when you no longer need it.

Answer 2

The obvious question is why you don't want to use the STL.

Assuming you have a reason, you would create an array of objects with something like Obj * op = new Obj[4];. Just remember to get rid of it with delete [] op;.

You can't do that with an object with no constructor that doesn't take arguments. In that case, I think the best you could do is allocate some memory and use placement new. It isn't as straightforward as the other methods.

Answer 3

Object2 *myArray[42];
for (int i = 0; i < 42; i++)
{
  myArray[i] = new Object2(param1, param2, ...);
}

Later on you will have to walk through the array and deallocate each member individually:

for (int j = 0; j < 42; j++)
{
  delete myArray[j];
}