CS 211 - 8/26/16

 pass-by-value = copies are send to the function, modifying the copy
                   does not change the original


 pass-by-reference = a reference to the original is sent to the function
                       modifying the reference does update the original

    the "pass-by-reference" syntax in C is often called "pass-by-address"

/*  void f1 ( int *a  , int sz )  */
void f1     ( int a[] , int sz , int *xp)
{

   sz = 10;
   *xp = 20;

}


int main()
{
  int arr[50];   /* allocates space for 50 integers on the stack */

  int *arr2;     /* allocates space for one address on the stack */
                 /* most often used for a dynamic array */

  int x = 0;

  /* allocates 50 integers for the dynamic array */
  int size2 = 50;
  arr2 = (int*) malloc ( size2 * sizeof(int) );   

 int i = 0;
 while ( MORE INPUT )
 {
      scanf ( "%d", &val);
  
      /* check if the array is full before adding the value */
      if ( i >= size2 )
      {
            /* add more space in the array - this code doubles the array size */
            int *temp;
            temp = (int *) malloc ( size2 * 2 * sizeof(int) );

            /* copy existing value to new memory space */
            int i;
            for ( i = 0 ; i < size2 ; i++)
               temp[i] = arr2[i];

            /* de-allocate the old memory space */
            free (arr2);

            /* update the variables to reflect the larger memory space */
            arr2 = temp;
            size2 = size2 * 2;

      }

      arr2[i] = val; 
      i++;


 }

 
  ..

  f1 ( arr,  size, &x );

}