# Multiple matches **URL:** \ **Category:** ruby-talk\ **Created:** [28 May 2009 13:34 UTC](https://rubytalk.org/t/multiple-matches/53622 "2009-05-28T13:34:55Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Guest2](https://avatars.discourse-cdn.com/v4/letter/g/439d5e/32.png) [@Guest2](https://rubytalk.org/u/Guest2)\ **Post date:** [28 May 2009 13:34 UTC](https://rubytalk.org/t/multiple-matches/53622/1 "2009-05-28T13:34:55Z")
Hi all, How to find out pattern'cat' in this string='ccccatgggctacatgggtcat' ? There are three 'cat' within the string and I want to return the position of each match. Although # match return the match , #pre\_match and #post\_match do the tricks but they only work for the first match. How about the 2nd, third match, and more? I try #scan(pattern) but it doesn't return the position for each match. I wonder how other handle this problem. Thanks, Li > **···** > > -- > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). ---
**Author:** ![Matt9](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@Matt9](https://rubytalk.org/u/Matt9)\ **Post date:** [28 May 2009 14:15 UTC](https://rubytalk.org/t/multiple-matches/53622/2 "2009-05-28T14:15:10Z")
It doesn't "return" the position but it does capture the position. s = 'ccccatgggctacatgggtcat' s.scan('cat') {puts Regexp.last\_match.begin(0)} The last regex match is always hanging around waiting for you to ask about it.... Hope that helps - m. > **···** > > Li Chen \ wrote: > > > I try #scan(pattern) but it doesn't return the > > position for each match. I wonder how other handle this problem. > > -- > matt neuburg, phd = matt@tidbits.com, [Matt Neuburg’s Home Page](http://www.tidbits.com/matt/) > Leopard - [http://www.takecontrolbooks.com/leopard-customizing.html](http://www.takecontrolbooks.com/leopard-customizing.html) > AppleScript - [http://www.amazon.com/gp/product/0596102119](http://www.amazon.com/gp/product/0596102119) > Read TidBITS! It's free and smart. [http://www.tidbits.com](http://www.tidbits.com) ---
**Author:** ![botp1](https://avatars.discourse-cdn.com/v4/letter/b/6de8d8/32.png) [@botp1](https://rubytalk.org/u/botp1)\ **Post date:** [28 May 2009 15:48 UTC](https://rubytalk.org/t/multiple-matches/53622/3 "2009-05-28T15:48:05Z")
> How to find out pattern'cat' in this string='ccccatgggctacatgggtcat' > ? There are three 'cat' within the string and I want to return the position of each match. there is String#index. there is no indexes, but you can build one if you like eg, > s =\> "ccccatgggctacatgggtcat" > class String > def indexes str, n=0 > n=index( str, n) >   if n >     [n] + indexes( str, n+=1) >   else >      >   end > end > end =\> nil > s.indexes "cat" =\> [3, 12, 19] the faster way is to loop, but i just want to test my recursion skill 😉 best regards -botp > **···** > > On Thu, May 28, 2009 at 9:34 PM, Li Chen \ wrote: ---
**Author:** ![Rob\_Biedenharn1](https://avatars.discourse-cdn.com/v4/letter/r/57b2e6/32.png) [@Rob\_Biedenharn1](https://rubytalk.org/u/Rob_Biedenharn1)\ **Post date:** [28 May 2009 14:51 UTC](https://rubytalk.org/t/multiple-matches/53622/4 "2009-05-28T14:51:31Z")
> > I try #scan(pattern) but it doesn't return the > > position for each match. I wonder how other handle this problem. > > It doesn't "return" the position but it does capture the position. > > s = 'ccccatgggctacatgggtcat' > s.scan('cat') {puts Regexp.last\_match.begin(0)} > > The last regex match is always hanging around waiting for you to ask > about it.... Hope that helps - m. > > -- matt neuburg, phd = matt@tidbits.com, [Matt Neuburg’s Home Page](http://www.tidbits.com/matt/) > Leopard - [http://www.takecontrolbooks.com/leopard-customizing.html](http://www.takecontrolbooks.com/leopard-customizing.html) > AppleScript - [http://www.amazon.com/gp/product/0596102119](http://www.amazon.com/gp/product/0596102119) > Read TidBITS! It's free and smart. [http://www.tidbits.com](http://www.tidbits.com) > s =\> "ccccatgggctacatgggtcat" > pos = =\> > while x = s.index('cat', (pos.last||-1)+1) >   pos \<\< x >   end =\> nil > pos =\> [3, 12, 19] String#index is the way to go. The second arg is the position to start looking for a match. .last==nil so it is a small trick to make the first loop test pass a 0 or 1 more than the previous match position. -Rob Rob Biedenharn [http://agileconsultingllc.com](http://agileconsultingllc.com) Rob@AgileConsultingLLC.com > **···** > > On May 28, 2009, at 10:15 AM, matt neuburg wrote: > > > Li Chen \ wrote: