CODEWITHSUNDEEP
c#regex
leon
leon

Reputation: 433

Regex filter out space at the end of line

Why does the following code find nothing in C# but works fine when I tested it online?

Match m = Regex.Match(@"abc
cd", "^abc[ \t]*$", RegexOptions.Multiline);

I am using this online regular expressions tester: http://derekslager.com/blog/posts/2007/09/a-better-dotnet-regular-expression-tester.ashx

I expect to get "abc"

Upvotes: 0

Views: 353

Answers (4)

leon
leon

Reputation: 433

I think I know what's happening here. In my text file the EOL is CRLF. But the C# regex treats the LF as the EOL(which is the '$'). So in my case the regex cannot find the CR and claim a failure. And @"^abc[ \t\r]*$" works.

Upvotes: 0

NeverHopeless
NeverHopeless

Reputation: 11233

As I understood you haven't captured any group so you get nothing as a result.

First try this:

Debug.Print(Regex.IsMatch(@"abc
cd", "^abc[ \t]*$", RegexOptions.Multiline).ToString());

You should get true, since there is a match.

Then try this: (notice the braces '()' after '^' and before '$')

Debug.Print(Regex.Match(@"abc
cd", "^(abc[ \t]*)$", RegexOptions.Multiline).ToString());

You should get a result in Output Window.

Hope it helps!

Upvotes: 0

Tim.Tang
Tim.Tang

Reputation: 3188

If you want to get abc you can use: ^abc.*$ instead.

If you want to get all, you can use: (?s)^abc.*$ instead.

I think your issue is: [ \t] can not match newline, so you also can change your code to match new line like this:

Match m = Regex.Match(@"abc
        cd", @"^abc[ \t\r]*$", RegexOptions.Multiline);

Upvotes: 1

Ehsan
Ehsan

Reputation: 32681

For a multiline string, you can remove the spaces at the end without using Regex.

string trimEnd = string.Join("\n", yourString.Split('\n').Select(x => x.TrimEnd()));

Upvotes: 1

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