I have this:

typedef string domanin_name;

And then, I try to overload the operator< in this way:

bool operator<(const domain_name & left, const domain_name & right){
    int pos_label_left = left.find_last_of('.');   
    int pos_label_right = right.find_last_of('.');

    string label_left = left.substr(pos_label_left);
    string label_right = right.substr(pos_label_right);
    int last_pos_label_left=0, last_pos_label_right=0;

    while(pos_label_left!=string::npos && pos_label_right!=string::npos){
        if(label_left<label_right) return true;
        else if(label_left>label_right) return false;

        else{
            last_pos_label_left = pos_label_left;
            last_pos_label_right = pos_label_right;

            pos_label_left = left.find_last_of('.', last_pos_label_left);
            pos_label_right = right.find_last_of('.', last_pos_label_left);

            label_left = left.substr(pos_label_left, last_pos_label_left);
            label_right = right.substr(pos_label_right, last_pos_label_right);
        }
    }
}

I know it's a strange way to overload the operator <, but I have to do it this way. It should do what I want. That's not the point.

The problem is that it enter in an infinite loop right in this line:

if(label_left<label_right) return true;

It seems like it's trying to use this overloading function itself to do the comparision, but label_left is a string, not a domain name!

Any suggestion?