[ale] [Fwd: Re: regexp, guru?]

[JD]

On 11/03/2011 04:28 PM, Geoffrey Myers wrote:
> Can someone explain:
> 
> ._%+- (first brackets)
> .- (second brackets)
> 
> 
> [a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]
> 


It looks like someone is trying to match email addresses.

The first [] is a list of all the characters allowed before the '@'.
Think of those as
 - letters or
 - numbers or
 - _ or
 - % or
 - . or
 - -
There must be at least 1 of those characters. That's what the trailing
'+' means after the close bracket, ].

The 2nd bracket says that the first character AFTER the '@' must be in
that list.
 - letters or
 - numbers or
 - . or
 - -

And I think is says 1 character (implied), but since there isn't a .$
the remaining characters in the line are ignored. This is not a
sufficient match for domain names, but I guess it works in a pinch.

I'd have to look up if the '-' in the brackets just before the closed
bracket, ']' was allowed.  The '.' (periods) inside the brackets ARE
periods - they do not match "any character" like they would outside
brackets.  I'm assuming regex with perl extensions - egrep, not grep syntax.

There is a javascript regex checker somewhere online. Can't recall where
now.