conditional preg_match in PHP

tried /[^fF\d+\s+]?[AF]?[\s+]?(\d+(\.\d{1,2})?-\d+(\.\d{1,2})?)/

want to match:

AF11-16 
AF 11-16
11-16
16.5-100

but do not match:

f3.5-5.6
F3.5-5.6
f 3.5-5.6
F 3.5-5.6

want to extract the focal开发者_高级运维 length range as result, like 11-16

do not know how to use conditional subpattern, any idea? thx!

---

^(?:af)?\s?([\d.]+)-([\d.]+)$

This one works for your dataset, as you can see here.

---

Instead of

\d+

use

\d{2,}

which will matches two or more digits.

/[^fF\d+\s+]?[AF]?[\s+]?(\d{2,}(\.\d{1,2})?-\d{2,}(\.\d{1,2})?)/