c++:array

#ifndef ARRAY_CLASS
#define ARRAY_CLASS
#include<iostream>
#include<cstdlib>
using namespace std;
#ifndef NULL
#define NULL 0
#endif
const enum ErrorType{invalidArraySize, memoryAllocationError, indexOutOfRange};

template <class T>
class Array{
private:
	T * alist;
	int size;
	void Error(ErrorType error, int badIndex = 0) const;
public:
	Array(int sz = 50);
	Array(const Array<T>&A);
	~Array(void);
	Array<T> &operator=(const Array <T> &rhs);
	T & operator[] (int i);
	operator T * (void) const;
	int ListSize(void) const;
	void Resize(int sz);
};
template<class T>
void Array<T>::Error(ErrorType error, int badIndex) const{
	char *errorMsgs[] = { "invalid array size", "memory allocation error", "invalid index:" };
	cout << errorMsgs[error];
	if (error == indexOutOfRange)
		cout << badIndex;
	cout << endl;
	exit(1);
}
template<class T>
Array<T>::Array(int sz){
	if (sz <= 0)
		Error(invalidArraySize);
	size = sz;
	alist = new T[size];
	if (alist == NULL)
		Error(memoryAllocationError);
}
template<class T>
Array<T>::~Array(void){
	delete[] alist;
}
template<class T>
Array<T>::Array(const Array<T> & X){
	int n = X.size;
	size = n;
	alist = new T[size];
	if (alist == NULL)
		Error(memoryAllocationError);
	T *srcptr = X.alist;
	T *destptr = alist;
	while (n--){
		*destptr++ = *srcptr++;
	}
}
template<class T>
Array<T>& Array<T>::operator= (const Array<T> &rhs){
	int n = rhs.size;
	if (size != n){
		delete[] alist;
		alist = new T[n];
		if (alist == NULL)
			Error(memoryAllocationError);
		size = n;
	}
	T *destptr = alist;
	T *srcptr = rhs.alist;
	while (n--){
		*destptr++ = *srcptr++;
	}
	return this;
}
template < class T>
T& Array<T>::operator[](int n)
{
	if (n<0 || n>size - 1)
		Error(indexOutOfRange, n);
	return alist[n];
}
template<class T>
Array<T>::operator T *  (void) const
{
	return alist;
}
template<class T>
int Array<T>::ListSize(void) const
{
	return size;
}
template<class T>
void Array<T>::Resize(int sz){
	if (sz <= 0)
		Error(invalidArraySize);
	if (sz == size)
		return;
	T * newlist = new T[sz];
	if (newlist == NULL)
		Error(memoryAllocationError);
	int n = (sz <= size) ? sz : size;
	T * srcptr = alist;
	T * destptr = newlist;
	while (n--)
		*destptr++ = *srcptr++;
	delete[] alist;
	alist = newlist;
	size = sz;
};
#endif

<pre class="cpp" name="code">#include<iostream>
#include<iomanip>
#include"Array.h"
int main()
{
	Array <int> A(10);
	int n;
	int primecount = 0, i, j;
	cout << "enter a value>=2 as upper limit for prime number:";
	cin >> n;
	A[primecount++] = 2;
	for (i = 3; i < n; i++){
		if (primecount == A.ListSize())
			A.Resize(primecount + 10);
		if (i % 2 == 0)
			continue;
		j = 3;
		while (j <= i / 2 && i%j != 0)
			j += 2;
		if (j>i / 2)
			A[primecount++] = i;
	}
	for (i = 0; i < primecount; i++){
		cout << setw(5) << A[i];
		if ((i + 1) % 10 == 0)
			cout << endl;
	}
	cout << endl;
}