Multiple regex options with C# Regex

Question

Assume I have this:

Regex.Replace("aa cc bbbb","aa cc","",RegexOptions.IgnoreCase);

But I also need to ignore white-spaces. So, I found an option IgnorePatternWhitespace, but how can I add several options to one regex.Replace?
Something like:

Regex.Replace("aa cc bbbb", "aa cc", "", 
    RegexOptions.IgnoreCase + RegexOptions.IgnorePatterWhitespace);

Update:
Thanks for answers but this option does not seem to work: here's a test example:

Regex.Replace("aa cc bbbb", "aacc", "", 
    RegexOptions.IgnoreCase | RegexOptions.IgnorePatterWhitespace);

"Does not seem to work" isn't very informative. What kind of behavior specifically are you after? — Chris Eberle
– Chris Eberle, Commented Nov 15, 2011 at 20:20
This simply does not makes sense as a question - especially once you see what the accepted answer is, but even outside of that context! — Code Jockey
– Code Jockey, Commented Nov 15, 2011 at 20:50
use & instead of +, Regex.Replace("aa cc bbb", "aa cc","", RegexOptions.IgnorePatternWhitespace & RegexOptions.IgnoreCase) — Chris Phelps
– Chris Phelps, Commented Aug 19, 2014 at 3:47
vb.net version = Regex.Replace("aa cc bbb", "aa cc", String.Empty, RegexOptions.IgnorePatternWhitespace And RegexOptions.IgnoreCase) — Chris Phelps
– Chris Phelps, Commented Aug 19, 2014 at 3:48

Liam · Accepted Answer · 2016-09-15 15:36:57Z

92

Use bitwise OR (|)

Regex.Replace("aa cc bbbb",
                "aa cc",
                "",
                RegexOptions.IgnoreCase | RegexOptions.IgnorePatterWhitespace);

edited Sep 15, 2016 at 15:36

Liam

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answered Nov 15, 2011 at 20:04

amit_g

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1 Comment

amit_g Over a year ago

@user194076, if you are expecting regular expression "aacc" to match "aa cc" in "aa cc bbbb", you are interpreting the RegexOptions incorrectly. You have to use something like "aa\s?cc" to match that i.e. use \s? to match optional whitespace. Regex.Replace("aa cc bbbb","aacc","",RegexOptions.IgnoreCase |

FailedDev · Accepted Answer · 2011-11-15 20:19:48Z

13

Regex.Replace("aa cc bbbb","aa cc","",RegexOptions.IgnoreCase | RegexOptions.IgnorePatterWhitespace);

Use the | operator.

Edit :

You got it completely wrong. RegexOption.IgnorePatterWhitespace ignores the whitespace in the regex so that you can do :

string pattern = @"
^                # Beginning of The Line
\d+              # Match one to n number but at least one..
";

You however think that ingoring whitespace makes "aa cc bbbb" into "aaccbbbb" which is thankfully wrong.

edited Nov 15, 2011 at 20:19

answered Nov 15, 2011 at 20:04

FailedDev

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Comments

Chris Eberle · Accepted Answer · 2011-11-15 20:03:27Z

8

According to MSDN:

A bitwise OR combination of RegexOption enumeration values.

So just use OPT_A | OPT_B

answered Nov 15, 2011 at 20:03

Chris Eberle

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Comments

Angelo · Accepted Answer · 2011-11-15 20:06:26Z

3

You can have as many RegexOptions as you like, just "OR" them with "|".

For example...

RegexOptions.Compiled | RegexOptions.IgnoreCase

answered Nov 15, 2011 at 20:06

Angelo

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Comments

Joe · Accepted Answer · 2011-11-15 20:28:35Z

2

IgnorePatternWhitespace
Eliminates unescaped white space from the pattern and enables comments marked with #. However, the IgnorePatternWhitespace value does not affect or eliminate white space in character classes.

so:

string result = Regex.Replace("aa cc bbbb","aa|cc","",RegexOptions.IgnoreCase).Trim();

answered Nov 15, 2011 at 20:28

Joe

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1 Comment

see Over a year ago

Please add a link to the original source you are quoting from.

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