PHP Regex: Match section of string based on part of section

I am trying to extract the age limitations from strings:

Example:
(Class 4) (0-110, 5yo+) 3m1f Good To Firm 18 fences
Return:
5yo+

Other examples would be 2yo, 3yo, 2-3yo, 4yo+, etc.

How do I match whole word if yo exists. I开发者_StackOverflow tried playing with \b but cannot get it to return the whole 5yo+ if yo is found :(

This worked for me, and should work for all of the examples you have given:

$str = '(Class 4) (0-110, 5yo+) 3m1f Good To Firm 18 fences';
if (preg_match('/[0-9-]+yo\\+?/', $str, $matches)) {
    echo "Matched: $matches[0]\n";
}

s/.*(\b[0-9-]+yo\+?\b).*/\1/

is the regex you seem to be looking for