Programming Forums > Application Development > C#

Arla · Mar 27th, 2008, 1:06 PM

Can't for the LIFE of me figure how to do this, and it seems like it would be stupidly simple.

I want a REGEX that will tell me if a string contains anything other than whitespace.

I've tried @"\s" but that just looks for a single whitespace (so a single whitespace anywhere in the text), @"\s*" but that seems to match anything (and everything?)

Where am I going wrong? I tried @"\s*^\S" but that again seems to match anything, what the hell am I doing wrong?

Arla · Mar 27th, 2008, 1:30 PM

Well this seemed to do it

@"^\s"

But I'm utterly baffled as to why, this comes up true for a string that's just whitespace, and false for a string with characters, which seems to be utterly backwards to me.

Ooble · Mar 27th, 2008, 3:28 PM

What that expression will do is look for one character of whitespace at the start of a string. Try a string with a space in front and it should match.

Try this:

(Toggle Plain Text)

@"^\s+$"

^ = beginning of string
\s = whitespace
+ = there should be one or more of the previous entity
$ = end of string

Arla · Mar 27th, 2008, 3:38 PM

Ooble, thanks, for some reason I had the ^ as meaning "not", somewhere I'm sure one of the many pages I read said that. Anyway, thanks again.

Ooble · Mar 27th, 2008, 3:48 PM

It can mean "not" in a character class. For example: ^[^xyz\s]+$ would match any string that doesn't contain whitespace or the characters "x", "y" or "z".

Regular-Expressions.info is a brilliant resource for regexes.

OpenLoop · Mar 27th, 2008, 5:41 PM

From wikipedia.org:

(Toggle Plain Text)

[^ ] 	Matches a single character that is not contained within the brackets. For example, [^abc] matches any character other than "a", "b", or "c". 

[^a-z] matches any single character that is not a lowercase letter from "a" to "z". As above, literal characters and ranges can be mixed.

^[hc]at matches "hat" and "cat", but only at the beginning of the string or line.

http://en.wikipedia.org/wiki/Regular_expression

Jabo · Mar 27th, 2008, 11:15 PM

doesn't string have an isemptyornull method in C#?

Jimbo · Mar 28th, 2008, 12:02 AM

Jabo - yes, but " " would return false from IsEmptyOrNull.

Jabo · Mar 28th, 2008, 12:04 AM

Quote:

Originally Posted by Arla

I want a REGEX that will tell me if a string contains anything other than whitespace.

Seems useful in this case to me.

Edit: no, maybe not, I see what you're saying.

Mar 27th, 2008, 1:06 PM	#1
Arla Hobbyist Programmer Join Date: Mar 2005 Posts: 135 Rep Power: 4	Regex, or I'm thick Can't for the LIFE of me figure how to do this, and it seems like it would be stupidly simple. I want a REGEX that will tell me if a string contains anything other than whitespace. I've tried @"\s" but that just looks for a single whitespace (so a single whitespace anywhere in the text), @"\s" but that seems to match anything (and everything?) Where am I going wrong? I tried @"\s^\S" but that again seems to match anything, what the hell am I doing wrong?

Mar 27th, 2008, 1:30 PM	#2
Arla Hobbyist Programmer Join Date: Mar 2005 Posts: 135 Rep Power: 4	Re: Regex, or I'm thick Well this seemed to do it @"^\s" But I'm utterly baffled as to why, this comes up true for a string that's just whitespace, and false for a string with characters, which seems to be utterly backwards to me.

Mar 27th, 2008, 3:28 PM	#3
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,435 Rep Power: 8	Re: Regex, or I'm thick What that expression will do is look for one character of whitespace at the start of a string. Try a string with a space in front and it should match. Try this: (Toggle Plain Text) @"^\s+$" @"^\s+$" `^` = beginning of string `\s` = whitespace `+` = there should be one or more of the previous entity `$` = end of string __________________ Me :: You :: Them

Mar 27th, 2008, 3:38 PM	#4
Arla Hobbyist Programmer Join Date: Mar 2005 Posts: 135 Rep Power: 4	Re: Regex, or I'm thick Ooble, thanks, for some reason I had the ^ as meaning "not", somewhere I'm sure one of the many pages I read said that. Anyway, thanks again.

Mar 27th, 2008, 3:48 PM	#5
Ooble I eat cake for breakfast. Join Date: Jul 2004 Location: In my box. Posts: 4,435 Rep Power: 8	Re: Regex, or I'm thick It can mean "not" in a character class. For example: `^[^xyz\s]+$` would match any string that doesn't contain whitespace or the characters "x", "y" or "z". Regular-Expressions.info is a brilliant resource for regexes. __________________ Me :: You :: Them

Mar 27th, 2008, 5:41 PM	#6
OpenLoop Expert Programmer Join Date: May 2005 Location: East Lansing, MI Posts: 647 Rep Power: 4	Re: Regex, or I'm thick From wikipedia.org: (Toggle Plain Text) [^ ] Matches a single character that is not contained within the brackets. For example, [^abc] matches any character other than "a", "b", or "c". [^a-z] matches any single character that is not a lowercase letter from "a" to "z". As above, literal characters and ranges can be mixed. ^[hc]at matches "hat" and "cat", but only at the beginning of the string or line. [^ ] Matches a single character that is not contained within the brackets. For example, [^abc] matches any character other than "a", "b", or "c". [^a-z] matches any single character that is not a lowercase letter from "a" to "z". As above, literal characters and ranges can be mixed. ^[hc]at matches "hat" and "cat", but only at the beginning of the string or line. http://en.wikipedia.org/wiki/Regular_expression

Mar 27th, 2008, 11:15 PM	#7
Jabo Not a user? Join Date: Sep 2007 Posts: 189 Rep Power: 1	Re: Regex, or I'm thick doesn't string have an isemptyornull method in C#?

Mar 28th, 2008, 12:02 AM	#8
Jimbo Expert Programmer Join Date: Feb 2006 Location: Bellevue, WA, USA Posts: 706 Rep Power: 3	Re: Regex, or I'm thick Jabo - yes, but " " would return false from IsEmptyOrNull. __________________ <insert disclaimer here> <insert shameless plug for Visual Studio here>

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Programming Forums > Application Development > C#

Regex, or I'm thick