Regex dot issue (C# .NET Framework 4.0)

Question

I guess the answer should be obvious but I don't understand

Regex reg = new Regex("a\r\n", RegexOptions.Singleline | RegexOptions.CultureInvariant);
Console.WriteLine(reg.IsMatch(".*a.*")); // writes FALSE

Why does this write false ? I thought that SingleLine allowed the dot to match anything, be it \r, \n, \r\n, \n\r or whatever ?

I think you are backwards, the pattern should be in the constructor of the Regex you have what you want to match there. — Kevin DiTraglia
– Kevin DiTraglia, Commented Jun 13, 2013 at 14:37

Kevin DiTraglia · Accepted Answer · 2013-06-13 14:40:28Z

3

You are backwards, you want to put the pattern in the constructor of the Regex rather than what you are trying to match. Try this:

Regex reg = new Regex(".*a.*", RegexOptions.Singleline | RegexOptions.CultureInvariant);
Console.WriteLine(reg.IsMatch("a\r\n")); // writes TRUE

answered Jun 13, 2013 at 14:40

Kevin DiTraglia

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1 Comment

Toto Over a year ago

Omg I can't believe it ... that's what I would call forgetting the bigger picture. Thank you for pointing that out ! I'm going to check it again tomorrow

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