Regex to match number specific number in a string

Question

I'm trying to fix a regex I create.

I have an url like this:

and I have to match the product ID (822).

I write this regex

(?<=prodotti\/).*(?<=\/)

and the result is "822/"

My match is always a group of numbers between two / /

Use a lookahead instead of a lookbehind, also use a reluctant quantifier instead of a greedy one `(?<=prodotti\/).*?(?=\/)`. [See the difference](http://stackoverflow.com/q/5319840) — HamZa, Mar 27 '14 at 09:04

ccjmne · Answer 1 · 2014-03-27T09:09:51.417

2

You're almost there!

Simply use:

(?<=prodotti\/).*?(?=\/)

instead of:

(?<=prodotti\/).*(?<=\/)

And you're good ;)

I've actually just changed two things:

replaced that lookbehind of yours ((?<=\/)) by its matching lookahead... so it asserts that we can match a / AFTER the last character consumed by .*.
changed the greediness of your matching pattern, by using .*? instead of .*. Without that change, in case of an url that has several / following prodotti/, you wouldn't have stopped to the first one.
i.e., given the input string: http://www.demo.it/prodotti/822/Panasonic/TXP46G20E.html, it would have matched 822/Panasonic.

edited Mar 27 '14 at 09:09

answered Mar 27 '14 at 09:03

ccjmne

Can you add a brief explanation... ? :) – Roberto Pezzali Mar 27 '14 at 09:04
now is ok. I'm learning regex so I want also to know what's my fault :) – Roberto Pezzali Mar 27 '14 at 09:11
Hey, you're right to ask, and actually my answer had no explanation before I edited it (within a very short time), so that was totally legitimate ;) – ccjmne Mar 27 '14 at 09:12
Don't forget to accept the answer it your problem is solved :) – ccjmne Mar 27 '14 at 09:45

1 Answers1