When implementing operator[] how should I include bounds checking?

Question

First of all I apologize for the long lead up to such a simplistic question.

I am implementing a class which serves as a very long 1 dimensional index on a space fil

Answer 1

Thanks to the comment on the C# feature in the post of Daniel Daranas I have managed to figure out a possible solution. As I stated in my question I am using the Qt libraries. There for I can use QVariant. QVariant can be set to an invalid state that can be checked by the function receiving it. So the code would become something like:

QVariant curvePoint::operator[](size_t index){
    QVariant temp;
    if(index > dimensions){
        temp = QVariant(QVariant::Invalid);
    }
    else{
        temp = QVariant(point[index]);
    }

    return temp;
}

Of course this has the potential of inserting a bit of gnarly overhead into the function so another possibility is to use a pair template.

std::pair curvePoint::operator[](size_t index){
    std::pair temp;
    if(index > dimensions){
        temp.second = false;
    }
    else{
        temp.second = true;
        temp.first = point[index];
    }
    return temp;
}

Or I could use a QPair, which has exactly the same functionality and would make it so that the STL need not be linked in.