programguru Posted June 11, 2008 Share Posted June 11, 2008 I am and really stumped, and I wanted to know if anyone could shed some light on my misunderstanding. Using the * in a match - of course * means zero or more of the previous char If sama*ntha matches: sammntha, samantha, and samaaantha why would it not match smantha ?? Can anyone explain this? I cannot find a sensible answer online and it driving me nuts! Quote Link to comment Share on other sites More sharing options...
TravisJRyan Posted June 11, 2008 Share Posted June 11, 2008 because its doing this match literally "sam" match "a" optionally and as many times match literally "ntha" http://www.regular-expressions.info/ And check out regex buddy. Handy tool Quote Link to comment Share on other sites More sharing options...
programguru Posted June 11, 2008 Author Share Posted June 11, 2008 So it appears to be matching everything literal after and before "a" but obviously "a" does not need to exist, so "smantha" would evaluate to false. So the correct explanation of * would be "looking for exact strings prior and after the previous char marked with *" Like: john*na johnona would return true johnnnna would return true jonnna would return false Am I getting this or dreaming? Quote Link to comment Share on other sites More sharing options...
Orio Posted June 11, 2008 Share Posted June 11, 2008 That's right. ab*c would match: ac abc abbc abbbc abbbbc etc' Orio. Quote Link to comment Share on other sites More sharing options...
lordfrikk Posted June 11, 2008 Share Posted June 11, 2008 So the correct explanation of * would be "looking for exact strings prior and after the previous char marked with *" Quantifier applies only to what is immediately in front of it, which could be either character, (non-)capturing parentheses, character class. Quote Link to comment Share on other sites More sharing options...
programguru Posted June 12, 2008 Author Share Posted June 12, 2008 lordfrikk, That makes sense, but I am not sure why would "sama*ntha" evaluate true for "sammntha"? As you can see "sama" is no part of it. TravisJRyan seemed to clarify this, but am I missing something? Quote Link to comment Share on other sites More sharing options...
TravisJRyan Posted June 12, 2008 Share Posted June 12, 2008 lordfrikk, That makes sense, but I am not sure why would "sama*ntha" evaluate true for "sammntha"? As you can see "sama" is no part of it. TravisJRyan seemed to clarify this, but am I missing something? I tried expr "sama*ntha" on this test case "sammntha" no matches Quote Link to comment Share on other sites More sharing options...
programguru Posted June 12, 2008 Author Share Posted June 12, 2008 TravisJRyan! I think I misunderstood you. I missed a char in my test ??? But I understand what you mean now. Thanks! Quote Link to comment Share on other sites More sharing options...
TravisJRyan Posted June 13, 2008 Share Posted June 13, 2008 TravisJRyan! I think I misunderstood you. I missed a char in my test ??? But I understand what you mean now. Thanks! Cool. . glad to help Quote Link to comment Share on other sites More sharing options...
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