Need help with this regex '^\*\|local7.*\s*\/[a-z]*'

blueskynet · 05-23-2012, 02:03 PM

Hi there,
As the title says, can someone explain to me what does that regex do? If possible, I would like to understand what each of these does.
\*

\|local7

.*

\s*

\/

[a-z]*

Thank you very much!

Tinkster · 05-23-2012, 02:58 PM

Can you please give us some context? Where did you dig this up, which tool/language
was it in? While 'regex' is a fairly well-known concept just about any tool you
touch that uses regex' will have a slightly different implementation.

If I assumed that the above was out of e.g., a perl snippet I'd break it up like so,
and would have to say that it's a weird (poorly written) regex:

Match anything that is either

Beginning of line, followed by any number of '\' followed by a backslash (the one behind the * doesn't make sense).

Code:

^\*\

or

Code:

the string local7 followed by any number of anything followed by any number of whitespace
followed by \/ followed by any number of lower case characters.

Code:

local7.*\s*\/[a-z]*

All up it makes little sense.

Cheers,
Tink

chrism01 · 05-23-2012, 07:04 PM

Quote:

While 'regex' is a fairly well-known concept just about any tool you
touch that uses regex' will have a slightly different implementation.

Absolutely(!); check out this book for details http://regex.info/blog/2006-07-21/218.
I've read it a couple of times; very good.

grail · 05-24-2012, 08:16 AM

As the other's have said, it will depend on where this came from and I will show you why, as this is how I interpreted it:

Code:

^      - start of the line / string
\*     - an asterisk, escaped so as not to be confused
\|     - a pipe, also escaped
local7 - string
.*     - zero or more of any character
\s*    - zero or more spaces
\/     - forward slash, escaped like others above
[a-z]* - zero or more lower case letters

As you can see, without reference the outcome is quite different to Tink's above.