To which example are you referring to? Example#2 uses $a == $b,
what is correct, because DateTime instances are compared.

In the German Manual, there is no example #2, there is just one.

I meant this:

function comp_func_cr($a, $b) 
    {
        if ($a->priv_member === $b->priv_member) return 0;
        return ($a->priv_member > $b->priv_member)? 1:-1;
    }

Ah, I see, thanks! The German translation of the array_udiff manual
page is currently not up-to-date, and the example violates strict
standards, so I suggest to ignore it. I'll update the translation
ASAP.

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.