When I print the id of a stream in a single expression it prints it backwards. Normally this is what comes out:

std::stringstream ss;

std::cout << ss.xalloc() << '\n';
std::cout << ss.xalloc() << '\n';
std::cout << ss.xalloc();

Output is:

4
5
6

But when I do it in one expression it prints backwards, why?

std::stringstream ss;

std::cout << ss.xalloc() << '\n'
          << ss.xalloc() << '\n'
          << ss.xalloc();

Output:

6
5
4

I know the order of evaluation is unspecified but then why does the following always result in the correct order:

std::cout << 4 << 5 << 6;

Can someone explain why xalloc behaves differently? Thanks.