RegEx: question mark

Parson · Post by **Parson** » Tue May 30, 2006 7:33 am

With this simplest RegEx-filter

/\/ad?[0-9]\.(gif|jpg|png)/

I'd like to catch images called ad1.gif or ad4.png. This works but I wonder why it doesn't match when the filename doesn't contain the number: ad.gif slips through.

Why that? I thought the question mark means "one or zero"?

mcm · Post by **mcm** » Wed May 31, 2006 3:13 am

Yes it does but it works on the preceding character which in this case is 'd' so 'a1.gif' or 'a4.gif' currently match as well. The filter should really be:

Code: Select all

/\/ad[0-9]?\.(gif|jpg|png)/

Parson · Post by **Parson** » Wed May 31, 2006 6:50 am

Ah, I see. Thanks for the help.