/**************************************************************/
// R. A. Hillyard
// pointer05.cpp
// November 2001
//
// Program to demonstrate dynamic arrays
//
// Create a dynamic array and then allow the user to
// adjust the size of the array
/**************************************************************/
#include<iostream>

using namespace std;

int const MinSize = 10;

int main()
  {
  int *ptr1, *ptr2;         //pointer to type int
  ptr1 = new int[MinSize];  //point to the first element of the new array

  int index;                //index variable for counter
  int temp;
  
  for(index = 0; index < MinSize; index++)   //assign initial values to new array
    {  ptr1[index] = 2 * index ;  }

  for(index = 0; index < MinSize; index++)   //print initial value of array elements
    {  cout << ptr1[index] << "  ";  }
  
  cout << "\n\nArray is now "<< MinSize << ": Enter new size >";
  cin >> temp;

  //save referance to array
  ptr2 = ptr1;           //ptr2 now points to the first element of the array

  ptr1 = new int[temp];  //now create array of new size
  
  if(temp > MinSize)     //If new array is larger than MinSize
    {
    for(index = 0; index < MinSize; index++)    //copy all elements of the old array 
      {  ptr1[index] = ptr2[index];  }

    for(index = MinSize; index < temp; index++) //ask for the rest of the elements
      {
      cout << "enter an int >";
      cin >> ptr1[index];
      }

    delete [] ptr2;     //give back the memory  

    for(index = 0; index < temp; index++)   //print new value of array elements
      {  cout << ptr1[index] << "  ";  }
    cout << endl;
    }//end if

  else  //new size smaller than old
    {
    for(index = 0; index < temp; index++)  //copy the first temp elements of the array   
      {  ptr1[index] = ptr2[index];  }

    delete [] ptr2;    //give back the memory  

    for(index = 0; index < temp; index++)  //print new value of array elements
      {  cout << ptr1[index] << "  ";  }
    cout << endl;
    }//end else
  }
/***********************Program Output*************************/
0  2  4  6  8  10  12  14  16  18  

Array is now 10: Enter new size >13
enter an int >5
enter an int >87
enter an int >22
0  2  4  6  8  10  12  14  16  18  5  87  22  

/************************Second Run****************************/
0  2  4  6  8  10  12  14  16  18  

Array is now 10: Enter new size >7
0  2  4  6  8  10  12