[Andreas]

PHP Code:

require_once('./includes/functions_misc.php');
$numbirthdays = fetch_character_count($birthdays, ','); 


But you might get a wrong result if a username contains a comma.
You could also count for '<a href="member.php?u' - I really doubt somebody would have this string in his username

IMHO the best solution would be to modify build_birthdays() to also put the number into cache. This way there would be zero overhead when displaying.
I'll post more details for this in a few minutes.

Update:
https://vborg.vbsupport.ru/showthread.php?t=61610