regular expression validation

I'm using the followin regular expression validator.  

ValidationExpression="^([a-zA-Z].*|[0-9].*)\.(((p|P)(d|D)(f|F))|((d|D)(o|O)(c|C))|((p|P)(d|D)(f|F))|((d|D)(o|O)(c|C)(x|X))|((t|T)(i|I)(f|F))|((t|T)(i|I)(f|F)(f|F))|((w|W)(p|P)(s|S))|((w|W)(p|P)(d|D))|((r|R)(t|T)(f|F)))$"

I don't understand the "=^([a-zA-Z].*|[0-9].*)\."
Can someone please help me translate this?

Thank you!
ocdcAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Terry WoodsIT GuruCommented:
^([a-zA-Z].*|[0-9].*)\.
means:
^  match the start of the string (or line, in multiline mode)
( start a capturing group
[a-zA-Z] match any one alphabetic character
.* match any number of any characters except newline
| logical OR applying within the capturing group
[0-9] match one digit
.* match any number of any characters except newline
) end the capturing group
\. match a . character

To summarise:

It looks like you're matching filenames. That part of the pattern will match and capture the entire filename (and path, if there) up to the extension as long as it starts with a letter or number, except it won't include the . character in the captured group.
0
Terry WoodsIT GuruCommented:
Examples:

For the string:
C:\foo\rhubarb\myfile.pdf
The part of the pattern you're asking about would capture:
C:\foo\rhubarb\myfile
but would match
C:\foo\rhubarb\myfile.

For the string:
123/456/rhubarb/myfile.pdf
The part of the pattern you're asking about would capture:
123/456/rhubarb/myfile
but would match
123/456/rhubarb/myfile.

For the string:
_somedir/rhubarb/myfile.pdf
The pattern would fail to match, as it doesn't start with a number or letter.
0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
.NET Programming

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.