Question

Sorry for the blurry title, I seem to be missing something.

I was hesitant to post this, because it seems so basic, but I can’t get it to work. My IDE tells me the following is incorrect. I have a class called IRatio which I want to be interchangeable with long double.

class
IRatio
{
    protected:
        long double 
        mValue;

    public:
        IRatio();

        IRatio(
            const IRatio& ir);

        IRatio(
            const long double& ld);

        IRatio&
        operator=(
            const IRatio& ir);

        IRatio&
        operator=(
            const long double& ld);

        operator long double() const;
};

Now I know that the following lines work:

IRatio n1(0.01f);
IRatio n2;
n2 = 0.02f;

However, to my complete suprise, this line doesn’t work:

IRatio n3 = 0.03f;

How do I get this to work? I assumed the copy constructor was called in this case? Or even if it was the assignment operator, I don’t mind! I know that std::string can do it.

std::string s = "hello!";

Thanks

Answer 1

Your code should work as is. That said, IRatio doesn’t manage any resources on its own, so you don’t need the copy constructor and assignment operator. This should do:

struct IRatio {
    IRatio() : d(0L) { }
    IRatio(long double d) : d(d) { }
    operator long double() const { return d; }
private:
    long double d;
};

int main(int argc, char* argv[])
{
    IRatio r = 0.02f;
    return 0;
}