Why can't I use this function with inside a function with const?

Question

I'm creating a bit array using unsigned chars for an assignment in my object oriented programming course. I was given the basic layout of what function we need. One was our Query function which is const.

this is my member data:

unsigned char* barray;         // pointer to the bit array
unsigned int arraySize;
static const unsigned int charSize = (sizeof(unsigned char) * 8);

and this is the function I'm having issues with:

bool BitArray::Query(unsigned int index)const{
unsigned int i = (Index(index)),
    p = Position(index);

unsigned int check = 1;
check = Move(check, p);

if ((check & barray[i]) == 0)
    return false;
else
    return true;

}

This function as well as an operator<< overload (also uses const keyword) get pissed off at me when I use my other functions in them (Index, Position, Move).

"IntelliSense: the object has type qualifiers that are not compatible with the member function "BitArray::Index" object type is const BitArray"

What is going on?

/* determine which element in array of chars to use */
unsigned int BitArray::Index(unsigned int n){
unsigned int index = (n / charSize);
if (((n % charSize) == 0) && (index < 0)){
    index -= 1;
}
return index;

}

/* determine index of bit of the particular char */
unsigned int BitArray::Position(unsigned int n){
unsigned int position = n;
position -= ((n / charSize) * charSize);
if (position == 0)
    position = charSize - 1;
else
    position--;
return position;

}

unsigned int BitArray::Move(unsigned int n, unsigned int m){
    return n << m;

}

Using Microsoft Visual Studio Express 2013

Answer 1

Those other functions need to be marked const as well. If they're not const, then you have no business calling them from a const function.