//CS2310 Exercise 14
//
//Name ___________________ SSN ______________________
//
//Chapter 15: p894 - 3
//
// IMPLEMENTATION FILE           (expArray.cpp)    
// Safe integer array class allows run-time specification 
// of size, prevents indexes from going out of bounds, 
// allows aggregate array copying and initialization.
// allows expanding the size of array when needed.
//
#include <iostream>
#include "expArray.h"

using namespace std;

ExpArray::ExpArray( /* in */  int arrSize )  			
       // Constructor.
		// PRE:  arrSize is assigned
		// POST:  IF arrSize >= 1 && enough memory THEN 
		// 	   Array of size arrSize is created with 	
		//        all elements == 0  ELSE error message.
{
	int i; 	
	if ( arrSize < 1 ) {
		cerr << "ExpArray constructor - invalid size: "
		     << arrSize << endl;
		exit(1);
	}

	arr = new  int[arrSize] ;	  // allocate memory 
	
	size = arrSize;

	for (i = 0; i < size;  i++)
		arr[i] = 0;
}	


void  ExpArray::Store ( /* in */ int val,  /* in */ int i ) 	 
		// PRE:  val and i are assigned
		// POST: IF 0 <= i < size of this array THEN
		// 	   arr[i] == val
		// 	   ELSE error message.

{
	
	if ( i < 0 || i >= size ) {
		cerr << "Store - invalid index : " << i << endl;
		exit(1) ;
	}

	arr[i] = val ;

}	


int  ExpArray::ValueAt ( /* in */ int i )  const		 
		// PRE:  i is assigned.
		// POST: IF 0 <= i < size THEN
		// 	   FCTVAL == arr[i] 
		// 	   ELSE halt with error message.
{
	
	if ( i < 0 || i >= size ) {
		cerr << "ValueAt - invalid index : " << i << endl;
		exit(1) ;
	}

	return  arr[i];

}	


ExpArray::~ExpArray( )	 
		// Destructor.
		// POST: Memory for dynamic array deallocated.
{
	delete [ ] arr ;
}

void ExpArray::ExpandBy( /* in */ int n)
		// Precondition:
		//		n > 0
		// Postcondition:
		//		Size of array has increased by n elements
		//   && All of the additional n elements equal zero
{
	int* tempArr;
	int newSize, i;
	
	newSize = size + n;

	tempArr = new // Write the missing code here: 
				  // create a new array of new size.

	for (i=0; i<size; i++)
		tempArr[i] = ValueAt(i);
	for (i=size; i<newSize; i++)
		tempArr[i] = 0;

	delete // Write the missing code here:
		   // delete the old array.
	arr = tempArr;
	size = // Write the missing code here:
		   // update size.
}

int main() {
	ExpArray oneArr(5);
	int i;

	for (i=0; i<5; i++)
		oneArr.Store(10*i, i);
	cout << "The array before expanding" << endl;
	for (i=0; i<5; i++)
		cout << oneArr.ValueAt(i) << "   ";
	cout << endl;

	oneArr.ExpandBy(5);
	for (i=5; i<10; i++)
		oneArr.Store(10*i, i);
	cout << "The array after expanding" << endl;
	for (i=0; i<10; i++)
		cout << oneArr.ValueAt(i) << "   ";
	cout << endl;

	return 0;
}