Go4Expert - more operator overloading

I get this error with this code:

error C2662: 'IntArray::translateIndexToZeroBased' : cannot convert 'this' pointer from 'const IntArray' to 'IntArray &'

Code:



int& IntArray::operator [](int index)

{

        static int sink;

        int zerobasedindex = translateIndexToZeroBased(index);

        if(zerobasedindex < 0 || zerobasedindex >= theSize)

        {

                cout<< "Problem with index (less than 0)" << endl;

                return sink;

        }



        return parray[zerobasedindex];

}



const int& IntArray::operator [](int index) const

{

        static int sink;

        int zerobasedindex = translateIndexToZeroBased(index);

        if(zerobasedindex < 0 || zerobasedindex >= theSize)

        {

                cout<< "Problem with index (l)" << endl;

                return sink;

        }

        return parray[zerobasedindex];

}