Using enum in loops and value consistency

Question

I\'m a big fan of C++\'s strong-typing features and what I like the most is to use enumerations while dealing with limited sets of data.

But enumerations lack some u

Answer 1

You can use a switch:

class Invalid {};
Prime& operator ++(Prime& p)
{
    switch(p)
    {
        case n00: return n01;
        case n01: return n02;
        case n02: return n03;
        case n03: return n04;
        case n04: return n05;
        case n05: return n06;
        case n06: return n07;
        case n07: return n08;
        case n08: return n09;
        case n09: return n10;
        case n10: return n11;
        case n11: return n12;
        case n12: return n13;
        case n13: return n14;
        case n14: return n15;
        // Here: 2 choices: loop or throw (which is the only way to signal an error here)
        case n15: default: throw Invalid();
    }
}

But note that this is not the right use of enums. I personally find this error-prone. If you want to enumerate integers, you can use an array of ints to do this, or for the case of prime numbers, a function (in mathematical sense: int nextPrime(int)).