Question

Suppose I have following template

template<unsigned char I, unsigned char F>
class FOO
{
   ....
}

In fact, I require (I >= F). If someone misuses

FOO<1, 2> a;

I hope to raise a compiling error. How to do that?

Thanks

Answer 1

One way may be C++11’s static_assert, which is similar to an assert, but checked at compile time:

template<unsigned char I, unsigned char F>
class FOO
{
    static_assert(I >= F, "I needs to be larger or equal to F");
    ...
};