This example works fine:
echo preg_replace("/\bI\b/u", 'we', "I can"); // we can
This one were russian letters are used does not work even though I use "u" modifier:
echo preg_replace("/\bЯ\b/u", 'мы', 'Я могу'); // still "Я могу"
So the question is what should I do to fix this?
Thanks.