Question about regular expression

ruby-talk
1

^ means from the beginning of a line ($ - end of line).
* means that a preceding character or group may be repeated 0 or more times.

Gennady.

···

-----Original Message-----
From: Eric Luo [mailto:eric.wenbl@gmail.com]
Sent: Mon 1/16/2006 23:17
To: ruby-talk ML
Subject: Re: Question about regular expression

Thanks very much, I really appreatiate your help

It does work, but I couldn't figure out what the ^ and * do? could you
explain that in more detail?

Thanks

2006/1/17, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov>:

On Tue, 17 Jan 2006, Eric Luo wrote:

> Thanks for your replay.
>
> To make the problem clear.
> I want to only change the regular expression, but not the code to
implement
> this function.
> Actually, the regular expression comes from a configurable table. I'll
be
> supposed to only have the privilege to update the table.
>
> So What I really want is a alternative way to in place of the regular
> expression
> (?<!STR )SNPB

   harp:~ > cat a.rb
   strings = "STR SNPB", "STR", "SNPB"

   re = %r/^ (?: (?:[^S]) | (?:S[^T]) | (?:ST[^R]) )* SNPB /ox

   strings.each do |string|
     permutations = string, "foo #{ string }", "#{ string } bar", "foo #{
string } bar"
     permutations.each do |permutation|
       puts "<#{ permutation }> matches" if re.match permutation
     end
   end

   harp:~ > ruby a.rb
   <SNPB> matches
   <foo SNPB> matches
   <SNPB bar> matches
   <foo SNPB bar> matches

hth.

-a
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