I am having a little trouble understanding regular expressions. My question is: How do you know when it is a good time to use parenthesis in a pattern. I know that if I would like to store a value in memory than I could use them. In an exercise in the Learning Perl book it says: Make a pattern that matches only lines containing either the word fred or wilma, followed by some whitespace, and then the word flintstone. So it should match the string: I am fred flintstone(with one or more spaces or tabs between the names.) Well my idea of what the code should look like is this: 
  /\bfred|wilma\s+flintstone\b/

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However, the book lists the code like this: 
  /\b(fred|wilma)\s+flintstone\b/

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I do not understand why the parenthesis are needed here. But I do see that if I take them away it causes problems because if I type just flintstone at the prompt it will not match. However, if I leave the parenthesis in the pattern as the book does than flintstone will match... could someone please clarify this for me..

-Warren E Bullock III wbullock@twcny.rr.com

Edit kudra, 2002-06-08 Changed title, added code tags

In reply to Parenthesis usage in Regular Expressions by WarrenBullockIII

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