From: kotin 76 <kotin76@...>
Date: 2011-07-28T18:20:30+09:00
Subject: Re: siimple string manuplation logic. But i did not getting correct one

Hi all,

thanks for all and especially for Gabriel.

I got solutions as per your suggestions.

Gabriel :

for my requirement i need second one

For the second:

%r{/media/.*} # match the literal /media/ followed by anything else up
to the end of the line


Its really great full for your support

Regards
Kotin



"Jesús Gabriel y Galán" <jgabrielygalan@gmail.com> wrote in post 
#1013491:
> On Thu, Jul 28, 2011 at 7:57 AM, kotin 76 <kotin76@yahoo.com> wrote:
>> #######################################################################
>> I would appreciate any answer.
> Based on this question and some previous ones, I think you need to
> read a little bit about regular expressions. For example:
> http://www.regular-expressions.info is a good starting point.
> For you to understand why the above code is failing, you need to know
> that \w+ matches any "word character" (the \w), one or more times (the
> +). And why is it stopping at the "-"? Because "-" is not a word
> character, so the regular expression stops matching there.
> To come up with a correct regular expression, you need to understand
> all the possible scenarios for that string. For example, maybe you can
> match all word characters, the dash, the underscore and the ".". Or
> maybe just the word characters plus the dash is enough. So please, let
> us know in plain English what your requirements are. For example:
>
> In a string such as "/dev/sdb  1949612  102404   1847208   6%
> /media/4B22-5451", I need to match everything after "/media/", which
> could be letters, numbers and dashes. Or:
>
> In a string such as "/dev/sdb  1949612  102404   1847208   6%
> /media/4B22-5451", I need to match everything after "/media/" up to
> the end of the line. Or:
>
> In a string such as "/dev/sdb  1949612  102404   1847208   6%
> /media/4B22-5451", I need to match everything after "/media/", up to
> the next whitespace or end of the line.
>
> I hope you get what I mean. You need to precisely define what are the
> conditions on which the matching has to stop or continue. Several
> examples based on the above:
>
> For the first one:
>
> %r{/media/[-\w]+}    # match the literal /media/ followed by one or
> more of word characters or dashes
> %r{/media/[-a-zA-Z0-9]+}  # match the literal /media/ followed by one
> or more of dash, lower or uppercase letters or numbers
>
> For the second:
>
> %r{/media/.*} # match the literal /media/ followed by anything else up
> to the end of the line
>
> For the third:
>
> %r{/media/[\S]*} # match the literal /media/ followed by anything else
> that is not a whitespace
>
> Also, even if you use the correct regexp for your case, you need to
> brush up the logic a little bit:
>
> string1 = "/dev/sdb  1949612  102404   1847208   6% /media/4B22-5451"
> if m2=string1.match( %r{/media/\w+} ).to_s then
>   if m2 =~ %r{/media/} then
>     puts "pass"
>     puts "mediastring = #{m2}"
>   end
> end
>
> To understand if the string matched or not while keeping the match
> data object, the idiom I use is:
>
> if m = string1.match(regexp)
>   # the matched string is now in m[0]
> end
>
> Also, you don't need the second if, because the regexp is a subset of
> the first one, so any string matched by the first regexp will match
> the second one. Again, I'd do:
>
> if m = string1.match(regexp)
>   # the matched string is now in m[0]
>   puts "pass"
>   puts "media string = #{m[0]}"
> end
>
> Now, you just need to come up with the correct regexp for all your
> possible cases and you are set.
>
> Hope this helps,
>
> Jesus.

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