C++ code improvement, array out of bounds - c++

Question

This is a class template for an Array. I overloaded the [ ] operator in hopes it would fix the "out of bounds" issue. The print outs work well, except if it falls out of range, the compiler enables the range by default and it displays a 6 digit number.
Perhaps looking for a better way to initialize the arrays with the appropriate element number for a better check and if it does fall out of range when looking up the element, display an error.
// implement the class myArray that solves the array index
// "out of bounds" problem.
#include <iostream>
#include <string>
#include <cmath>
using namespace std;
template <class T>
class myArray
{
private:
T* array;
int begin;
int end;
int size;
public:
myArray(int);
myArray(int, int);
~myArray() { };
void printResults();
// attempting to overload the [ ] operator to find correct elements.
int operator[] (int position)
{if (position < 0)
return array[position + abs(begin)];
else
return array[position - begin];
}
};
template <class T>
myArray<T>::myArray(int newSize)
{
size = newSize;
end = newSize-1;
begin = 0;
array = new T[size] {0};
}
template <class T>
myArray<T>::myArray(int newBegin, int newEnd)
{
begin = newBegin;
end = newEnd;
size = ((end - begin)+1);
array = new T[size] {0};
}
// used for checking purposes.
template <class T>
void myArray<T>::printResults()
{
cout << "Your Array is " << size << " elements long" << endl;
cout << "It begins at element " << begin << ", and ends at element " << end << endl;
cout << endl;
}
int main()
{
int begin;
int end;
myArray<int> list(5);
myArray<int> myList(2, 13);
myArray<int> yourList(-5, 9);
list.printResults();
myList.printResults();
yourList.printResults();
cout << list[0] << endl;
cout << myList[2] << endl;
cout << yourList[9] << endl;
return 0;
}

Answer 1

First of all, your operator[] is not correct. It is defined to always return int. You will get compile-time error as soon as you instantiate array of something, that is not implicitly convertible to int.
It should rather be:
T& operator[] (int position)
{
//...
}
and, of course:
const T& operator[] (int position) const
{
//you may want to also access arrays declared as const, don't you?
}
Now:
I overloaded the [ ] operator in hopes it would fix the "out of bounds" issue.
You didn't fix anything. You only allowed clients of your array to define custom boundaries, nothing more. Consider:
myArray<int> yourList(-5, 9);
yourList[88] = 0;
Does your code check for out-of-bounds cases like this one? No.
You should do it:
int operator[] (int position)
{
if((position < begin) || (position > end)) //invalid position
throw std::out_of_range("Invalid position!");
//Ok, now safely return desired element
}
Note, that throwing exception is usually the best solution in such case. Quote from std::out_of_range doc:
It is a standard exception that can be thrown by programs. Some components of the standard library, such as vector, deque, string and bitset also throw exceptions of this type to signal arguments out of range.

Answer 2

An better option to redefining an array class is to use the containers from the std library. Vector and array(supported by c++11). They both have an overloaded operator [] so you can access the data. But adding elements using the push_back(for vector) method and using the at method to access them eliminates the chance or getting out of range errors, because the at method performs a check and push_back resizes the vector if needed.