# MatchData captures... expected two items, but got one? **URL:** \ **Category:** Ruby\ **Created:** [March 2, 2010, 2:15am UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406 "2010-03-02T02:15:32Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 2:15am UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/1 "2010-03-02T02:15:32Z")
Looking at the MatchData docs: [http://ruby-doc.org/core/classes/MatchData.html#M001278](http://ruby-doc.org/core/classes/MatchData.html#M001278) It looks like I should be able to get an array from .captures with every match. I swear I’ve done this before, but I was teaching a class today and couldn’t figure out what’s going on in this simple example… maybe I typed something wrong and just need another pair of eyes. $ irb > > test = “word1 foo word2” > > =\> “word1 foo word2” > > m = test.match /(word.)/ > > =\> #\ > > m.captures > > =\> [“word1”] testing the same string and expression in [http://www.rubular.com](http://www.rubular.com) yields two matches $ ruby -v ruby 1.8.7 (2009-06-12 patchlevel 174) [i686-darwin9.7.0] Can anyone give me a clue? Thanks in advance, Sarah ---
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 2:37am UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/2 "2010-03-02T02:37:52Z")
On Mon, Mar 1, 2010 at 7:15 PM, Sarah A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > > > test = “word1 foo word2” > > > ruby 1.8.7 (2009-06-12 patchlevel 174) [i686-darwin9.7.0] > > Can anyone give me a clue? > > ## Thanks in advance, Sarah > > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/). > > Not sure what the answer is with match, I usually use scan like this: test = “word1 foo word2” m = test.scan(/word./) m # =\> [“word1”, “word2”] ---
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 5:48am UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/3 "2010-03-02T05:48:40Z")
Josh C. wrote: > > Not sure what the answer is with match, I usually use scan like this: > > test = “word1 foo word2” > m = test.scan(/word./) > m # =\> [“word1”, “word2”] Thanks Josh. I should have mentioned that I found that work-around. I just need to be able to explain why match doesn’t seem to work the way the documentation says it should – at least by my reading of it. Best, Sarah ---
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 6:58am UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/4 "2010-03-02T06:58:20Z")
On Tue, Mar 2, 2010 at 12:48 PM, Sarah A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > …just need to be able to explain why match doesn’t seem to work the way > the documentation says it should – at least by my reading of it. your match/regex captured only one… try eg, > m = test.match /(word.).\*?(word.)/ > =\> #\ > m.captures > =\> [“word1”, “word2”] ---
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 12:42pm UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/5 "2010-03-02T12:42:32Z")
2010/3/2 Sarah A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > Josh C. wrote: > > > > Not sure what the answer is with match, I usually use scan like this: > > > > test = “word1 foo word2” > > m = test.scan(/word./) > > m # =\> [“word1”, “word2”] > > Thanks Josh. I should have mentioned that I found that work-around. I > just need to be able to explain why match doesn’t seem to work the way > the documentation says it should – at least by my reading of it. Where exactly is the difference between the functionality and the description? Kind regards robert ---
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 4:33pm UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/6 "2010-03-02T16:33:54Z")
Robert K. wrote: > Where exactly is the difference between the functionality and the > description? > > Kind regards > > robert The docs are correct, but not particularly helpful in their description. It is not ideal to use a word in its definition: captures: “Returns the array of captures” [http://ruby-doc.org/core/classes/MatchData.html#M001278](http://ruby-doc.org/core/classes/MatchData.html#M001278) If I had looked closer at the example I might have figured it out, since upon reflection it is pretty standard regex. My attempts at debugging with rubular further confused me since it reports two matches from the single capture expression. botp pointed out that I needed to specify one capture per result. Which the ruby-doc example also illustrates: f1,f2,f3,f4 = /(.)(.)(\d+)(\d)/.match(“THX1138.”).captures f1 #=\> “H” f2 #=\> “X” f3 #=\> “113” f4 #=\> “8” I was confused by the rubular experiment and also by the String.scan docs [class String - RDoc Documentation](http://ruby-doc.org/core/classes/String.html#M000812) where captures are described as “groups”… or maybe they were just referring to the result of evaluating the capture with a scan. Thanks everyone for your help! Sarah ---
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 5:48pm UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/7 "2010-03-02T17:48:05Z")
2010/3/2 Sarah A. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > Robert K. wrote: > > > Where exactly is the difference between the functionality and the > > description? > The docs are correct, but not particularly helpful in their description. Ah, OK. > I was confused by the rubular experiment and also by the String.scan > docs [class String - RDoc Documentation](http://ruby-doc.org/core/classes/String.html#M000812) where captures > are described as “groups”… or maybe they were just referring to the > result of evaluating the capture with a scan. Whenever I need to find out things like these I test with IRB. That works pretty well for me. Maybe it’s an option for you, too. > Thanks everyone for your help! You’re welcome! Kind regards robert ---
**Author:** ![sackerson](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/59ef9b/32.png) [@sackerson](https://www.ruby-forum.com/u/sackerson)\ **Post date:** [March 2, 2010, 7:11pm UTC](https://www.ruby-forum.com/t/matchdata-captures-expected-two-items-but-got-one/184406/8 "2010-03-02T19:11:12Z")
> Thanks Josh. I should have mentioned that I found that work-around. I > just need to be able to explain why match doesn’t seem to work the way > the documentation says it should – at least by my reading of it. Yeah, appears match only matches the first match. Sounds like a forest fire! -rp