Fix regex pattern in visual studio C#

Question

I am using this regex pattern (\[|)(\w\w \d*)(\; |\*|\s|]?, )((\"(\w)\"|\((.\w)\))|)(\]|)|(\[\w\w \d\]) to match the below string:

Hp 0; Ks 1; Ks 2

I have tested this pattern in https://regex101.com/, and everything works fine, complete string is matched Hp 0; Ks 1; Ks 2 . But the same pattern in Visual Studio (.Net Framework) match just Hp 0; Ks 1;.

Can anyone help me where is the problem ?

I have written this code in VS:

 StringBuilder matchedSignalbegriff = new StringBuilder();

            var pattern = "(\\[|)(\\w\\w \\d*)(\\; |\\*|\\s|]?, )((\"(\\w)\"|\\((.\\w)\\))|)(\\]|)|(\\[\\w\\w \\d\\])";
            Regex rgx = new Regex(pattern);

            foreach (Match match in rgx.Matches(stringToTest))
            {
                matchedSignalbegriff.Append(match);
            }

You'll be a lot happier writing verbatim string literals (i.e. literals prefaced with a @) when doing Regexes. Something like var pattern = @"(\[|)(\w\w etc. In all likelihood, you have a misplaced escape character if it works in a tool and not in your code — Flydog57
– Flydog57, Commented Mar 5, 2022 at 23:02
Apart from not using a verbatim string as @Flydog57 suggests, is there a reason why your pattern is so complicated? What other input variations are you trying to match? — PeterE
– PeterE, Commented Mar 5, 2022 at 23:24
Even if i use your pattern in regex101.com, Hp 0; and Ks 1; are two separate matches. To match the whole string Hp 0; Ks 1; Ks 2, you could use Regex rgx = new Regex(@"(\[|)((\w\w \d*)((\; )?|\*|\s|]?, ))*((\""(\w)\""|\((.\w)\))|)(\]|)|(\[\w\w \d\])"); — johnmoarr
– johnmoarr, Commented Mar 5, 2022 at 23:27
@PeterE it looks complicated, because this is just one of 200 matches! This pattern match 200 different strings =) — DevOp
– DevOp, Commented Mar 6, 2022 at 9:25
@DevOp maybe then you have to describe what you want to achieve a bit more in detail. While using the regex I provided, the whole string you described is matched. You can check it out in this .net fiddle. — johnmoarr
– johnmoarr, Commented Mar 6, 2022 at 11:08

The fourth bird · Accepted Answer · 2022-03-06 14:18:16Z

1

Your pattern does not match the whole string or all 3 parts on regex101, see https://regex101.com/r/2ldB6Z/1

That is because this part (\; |\*|\s|]?, ) has to match at least one of the listed character(s) which is not present in Hp 0; Ks 1; Ks 2

Using a construct like (\[|) in your pattern makes it optional due to the | at the end.

To make the pattern match all 3 parts, you can add asserting the end of the string in the alternation in your pattern:

var pattern = @"(\[|)(\w\w \d*)(\; |\*|\s|]?, |$)((""(\w)""|\((.\w)\))|)(\]|)|(\[\w\w \d\])";

See a .NET regex demo and a C# demo

As an alternative for a more basic pattern to match the example string:

\w\w \d+(?:; \w\w \d+)*

See another regex demo

answered Mar 6, 2022 at 14:18

The fourth bird

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