Re: Regex Help

More than looking inefficient, it looks unnecessarily cluttered, which can contribute to bugs:

[\D]? is the same as \D?. This is repeated four times.
[0|1] is probably a mistake; character classes don't use alternation, and I don't see any | characters in your sample input. You probably mean [01]
\D?\d{4} is repeated twice in a row. How about (?:\D?\d{4}){2} ?

Making those changes would yield:

9818\D?9[01]\D?\d{2}(?:\D?\d{4}){2}
[download]

Now with the /x modifier, you can further clarify things like this:

m/
  9818        # A literal.
  \D?         # Optional non-digit.
  [01]        # Require a zero or a one.
  \D?         # Another optional non-digit.
  \d{2}       # Require two digits.
  (?:         # Group but don't capture.
    \D?       # Another optional non-digit.
    \d{4}     # Followed by four digits.
  ){2}        # Repeated twice.
/x
[download]

As for efficiency, what problems are you encountering? If you're dealing with huge input you're probably IO bound anyway.

Dave

Comment on Re: Regex Help Select or Download Code

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Re^2: Regex Help by gautamparimoo (Beadle) on Mar 25, 2013 at 08:48 UTC
Thnks davido your regex just cleaned it up. But what modifiers or assertion should i use to limit matching such that it does not match it in different lines in a text file ie only match if this pattern is specified in one line not across different lines. Pl tell?	[reply]
Re^3: Regex Help by davido (Cardinal) on Mar 25, 2013 at 08:55 UTC
Replace `\D?` with a more explicit character class. `\D` will match anything that is not a numeric digit. Newlines (`\n`) are included in "anything that is not a numeric digit". Dave	[reply] [d/l] [select]
Re^4: Regex Help by gautamparimoo (Beadle) on Mar 25, 2013 at 09:29 UTC
Exactly what i was trying to say.. How to do tell it to \D except \n ?	[reply]
Re^5: Regex Help by Anonymous Monk on Mar 25, 2013 at 10:17 UTC
Re^6: Regex Help by davido (Cardinal) on Mar 25, 2013 at 16:29 UTC
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