splitting text after 25 words

Hi all, I'd like to split a text block at 25 words, as a teaser for the full article. Now I know how to split at a certain character, but i don't want a half word or anything, so I want (i guess) to hunt for the 25th occurence of " " (a space), and split $text into two new variables, $text_a and $text_b. Then I'll prolly want append something like "... click here to read more" on the end of $text_a. Seems easy enough, but I can't see anything in the manual about splitting on a numbered occurence of a string (but I could be looking in the wrong spot :) Running PHP4 BTW Thanks heaps in advance Justin French