Data Structures, Algorithms, & Applications in C++
Chapter 5, Exercise 23

template<class T>
class arrayListWithLeftShift : public arrayList<T> 
{
   public:
      // constructor and destructor
      arrayListWithLeftShift(int initialCapacity = 10)
           : arrayList<T> (initialCapacity) {}

      void leftShift(int theAmount);
};

template<class T>
void arrayListWithLeftShift<T>::leftShift(int theAmount)
{// Left shift by i elements.


   if (theAmount <= 0)
      return; 
      // could throw exception when i < 0 or do a right shift by i

   int newSize = 0;
   if (theAmount < listSize)
   {// list is not empty after the shift
      newSize = listSize - theAmount;

      // left shift elements with higher index >= i
      copy(element + theAmount, element + listSize, element);
   }

   // destroy uneeded elements
   for (int i = newSize; i < listSize; i++)
      element[i].~T(); 

   listSize = newSize;
}