How to make this regex allow spaces c#

Question

I have a phone number field with the following regex:

[RegularExpression(@"^[0-9]{10,10}$")]

This checks input is exactly 10 numeric characters, how should I change this regex to allow spaces to make all the following examples validate

1234567890
12 34567890
123 456 7890

cheers!

Answer 1

This works:

^(?:\s*\d\s*){10,10}$

Explanation:

^ - start line
(?: - start noncapturing group
\s* - any spaces
\d - a digit
\s* - any spaces
) - end noncapturing group
{10,10} - repeat exactly 10 times
$ - end line

This way of constructing this regex is also fairly extensible in case you will have to ignore any other characters.

Answer 2

Use this:

^([\s]*\d){10}\s*$

I cheated :) I just modified this regex here:

Regular expression to count number of commas in a string

I tested. It works fine for me.

Answer 3

Depending on your problem, you might consider using a Match Evaluator delegate, as described in http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.matchevaluator.aspx

That would make short work of the issue of counting digits and/or spaces