Question

So I have this array of pointers

image* [] myArray;

And I copy the objects in the array into a new, larger array.

for (int i=0; i<maxObjects; i++){
  newArray[i] = myImages[i];
}
for (int i=maxObjects; i<newMaxObjects; i++){
  newArray[i] = NULL;
}

The point of this is to resize my array. Then I delete myArray:

delete [] myArray;

Which, I presume deletes the objects from the array, as well as the pointer to those objects. Now I want to declare myArray again

image* [] myArray;

and set this to point to my new, larger array.

myArray = newArray;

This is where I get lost: now I’ve got two pointers to the same array. myArray points to the same thing as newArray, right? Or, am i wrong, and myArray now points to newArray (the pointer), which points to the object I want?

My main questions: How do I delete the temporary pointer myArray without deleting the data it points to? Also, how do I assign the myArray pointer directly to the data, rather than pointing to another pointer? Am I doing it right or is there a better way to do what I’m doing?

Answer 1

• This is where I get lost: now I’ve
  got two pointers to the same array.
  myArray points to the same thing as
  newArray, right? Or, am i wrong, and
  myArray now points to newArray (the
  pointer), which points to the object
  I want?

myArray is assigned the same value as newArray, which is the memory location of the first element of newArray. After you say myArray = newArray; , if you assign newArray to NULL, myArray will still point to the datapointers.

• My main questions: How do I delete
  the temporary pointer myArray without deleting the data it points to?

myArray = NULL; Will just reset the pointer. delete [] myArray; will deallocate the memory you saved for the pointers that point to your data, but WILL NOT delete the actual data.

• Also, how do I assign the myArray
  pointer directly to the data,
  rather than pointing to another
  pointer? Am I doing it right or is
  there a better way to do what I’m
  doing?-

Using the indirection operator (*) on a pointer which retrieves the data it points to. newerArray will contain an array of pointers to data. newestArray is an array of the data.

image* newerArray = new (image*)[size];
for (int i = 0; i < size; i++)
{
    newerArray[i] = *(myArray[i]);
}



image newestArray = new image[size];
for (int i = 0; i < size; i++)
{
    newestArray[i] = *(*(myArray[i]));
}