.NET RegEx help

Question

I am very inexperienced when it comes to regular expressions. What I'm trying to do is iterate through a list of strings and try to locate strings that are of a certain pattern. The strings I am interested in will be in the form of "some text ***{some text}***" How do I write a RegEx to match up to? I was trying this:

Regex expression = new Regex("***");

but this gives me an error. parsing "***" - Quantifier {x,y} following nothing.

Can someone point me in the right direction?

I'm trying to loop through select list options and add a css class to the options that are relevant.

Regex expression = new Regex("***");
foreach (ListItem li in listItemCollection)
{
    if (expression.IsMatch(li.Value))
        li.Attributes.Add("class", "highlight1");
}

but this obviously isn't working.

Any help is appreciated, ~ck in San Diego

Fredrik Mörk · Accepted Answer · 2009-07-21 20:15:18Z

9

You need to escape the asterisk, as it's a valid metacharacter in RegExp.

Regex expression = new Regex(@"\*\*\*");

edited Jul 21, 2009 at 20:15

Fredrik Mörk

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answered Jul 21, 2009 at 20:13

brettkelly

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1 Comment

Derek Slager Over a year ago

Regex.Escape is also useful: new Regex(Regex.Escape("***"));

Brian Dukes · Accepted Answer · 2009-07-21 20:29:12Z

3

If all you're trying to do is match three asterisks, why not just use the string.Contains method instead of a regular expression?

foreach (ListItem li in listItemCollection)
{
    if (li.Value.Contains("***"))
        li.Attributes.Add("class", "highlight1");
}

answered Jul 21, 2009 at 20:29

Brian Dukes

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1 Comment

SolutionYogi Over a year ago

+1 for thinking about the actual problem instead of just fixing the code. This is a better idea instead of using Regex.

Community · Accepted Answer · 2017-05-23 12:19:14Z

3

* has a special meaning in regular expression.

If you are looking to match 3 asteriks, try

Regex expression = new Regex(@"\*\*\*");

EDIT:

If you are only trying to verify if a string contains "***", look at bdukes' answer.

edited May 23, 2017 at 12:19

CommunityBot

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answered Jul 21, 2009 at 20:13

SolutionYogi

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Comments

Andrew Hare · Accepted Answer · 2009-07-21 20:14:31Z

2

Try something like this:

\*\*\*[^\*]+\*\*\*

answered Jul 21, 2009 at 20:14

Andrew Hare

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Comments

Martin Brown · Accepted Answer · 2009-07-21 21:25:32Z

0

If you are going to test out regexes, get an application for testing. Any of these would be a good start. I've been attached to Chris Sells's tester for a long time but there are lots out there.

edited Jul 21, 2009 at 21:25

Martin Brown

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answered Jul 21, 2009 at 20:20

hughdbrown

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Comments

Alan Moore · Accepted Answer · 2009-07-22 06:07:05Z

0

You should try this regex pattern

\*{3}\{[^\}]*}\*{3}

This will find ***{some text}***

If you want the text before the * you should use this one

^[\w\s]*\*{3}\{[^\}]*\}\*{3}

^ - beginning of the input
[\w\s]* any char in a-z, A-Z, 0-9, _ and white space, 0 or more times
\*{3} three asterisks
\{ match {
[^\}]* any char except } 0 or more times
\} match }
\*{3} match three asterisks

edited Jul 22, 2009 at 6:07

Alan Moore

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answered Jul 22, 2009 at 1:29

Cédric Boivin

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1 Comment

Alan Moore Over a year ago

@Cédric, notice the correction re: \w - it matches digits, too. Also, in some regex flavors \w matches letters and digits from all writing systems, not just the ASCII ones.

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