What is the "" operator that I saw in GoingNative2012

Question

I recently watched GoingNative2012 about, of course, C ++ 11.

In the Bjarne Stroustrup section, I found that there was an interesting operator function that was like belows.

constexpr Value<Second> operator""s(long double d)
{
     return Value<Second>(d);
}

Well, besides constexpr, which looks like a new keyword in C ++ 11,

I never knew that “overloaded”?

Is this one of the new features in C ++, although I could not test it with VS 2010?

Thanks in advance.

Answer 1

This is the new C ++ 11 core language feature: user-defined characters