Using RegEx to ignore empty strings and spaces

Question

I have the following simple test which doesnt return true for some reason.

string[] test = new string[] { "A", " ", " ", "D", "" };
Regex reg = new Regex(@"^[A-Z]\s$");
bool ok = test.All(x => reg.IsMatch(x));

I've also tried putting the \s inside the square brackets but that doesn't work either

I want to make sure that all characters in the array that are not empty or blank spaces match A-Z.

I realise I could do a Where(x=>!String.IsNullorEmpty(x) && x != " ") before the All but I thought Regex could handle this scenario

In .Net 4 you also have String.IsNullOrWhiteSpace which removes the need for && x != " ". Can't help with regex though, sorry (I suck at it) — Smudge202
– Smudge202, Commented Jul 5, 2011 at 16:17
Please try to be clear about where you mean strings, and where you mean characters: "All characters in the array that are not empty strings" - characters and strings aren't the same thing. — Jon Skeet
– Jon Skeet, Commented Jul 5, 2011 at 16:19
@Jon: It's still not clear what you mean, because you've got an array of strings. I think it would really help if you could reduce your example to matching a single string. Once you've worked out how to get a single string to work how you want, you can move on to match multiple strings with All trivially. — Jon Skeet
– Jon Skeet, Commented Jul 5, 2011 at 16:22

Jon Skeet · Accepted Answer · 2011-07-05 16:17:13Z

5

I think you want:

Regex reg = new Regex(@"^[A-Z\s]*$");

That basically says "the string consists entirely of whitespace or A-Z".

If you want to force it to be a single character or empty, just change it to:

Regex reg = new Regex(@"^[A-Z\s]?$");

answered Jul 5, 2011 at 16:17

Jon Skeet

1.5m893 gold badges9.3k silver badges9.3k bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Jon Over a year ago

Do you mean it will ignore the whitespace ie/it wont try and match against those elements

Jon Skeet Over a year ago

@Jon: I don't know what you mean. It won't ignore the whitespace - it'll match the whitespace. So "A B C" will match the first regex, as will "A ", but "A0" won't.

Jon Over a year ago

I think I need to do the Where clause to strip the whitespace and empties because the All will run over every element

Jon Skeet Over a year ago

@Jon: It's still not clear what you're trying to do. The first regular expression will match whitespace and empty strings too, so you don't need to strip them out first.

Alan Moore Over a year ago

@Jon-not-Skeet: If you add the line Console.WriteLine(ok); to the code in your question, then using either of the regexes in this answer, the output is True. Isn't that what you want?

|

Bolu · Accepted Answer · 2011-07-05 16:24:33Z

1

Enumerable.All<TSource> Method Determines whether all elements of a sequence satisfy a condition.

answered Jul 5, 2011 at 16:24

Bolu

8,8065 gold badges40 silver badges75 bronze badges

1 Comment

Jon Over a year ago

Yup I think I need the Where clause!

svick · Accepted Answer · 2011-07-05 16:17:31Z

0

The regular expression ^[A-Z]\s$ says: two-character string, whose first character is A-Z and the second is a white space. What you actually want is ^[A-Z\s]*$.

answered Jul 5, 2011 at 16:17

svick

247k54 gold badges407 silver badges535 bronze badges

Collectives™ on Stack Overflow

Using RegEx to ignore empty strings and spaces

3 Answers 3

7 Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

7 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related