.NET Regex dot character matches carriage return?

Question

Every single flavor of regex I have ever used has always had the \".\" character match everything but a new line (\\r or \\n)... unless, of course, you enable the single-lin

Answer 1

I ran into this same issue when writing Regex Hero. It is a little bizarre. I blogged about the issue here. And that led to me adding a feature to the tester to enable/disable CRLFs. Anyway, for some reason Microsoft chose to use \n (line feeds) to mark line endings.

(UPDATE) The reason must be related to this:

Microsoft .NET Framework regular expressions incorporate the most popular features of other regular expression implementations such as those in Perl and awk. Designed to be compatible with Perl 5 regular expressions, .NET Framework regular expressions include features not yet seen in other implementations, such as right-to-left matching and on-the-fly compilation. http://msdn.microsoft.com/en-us/library/hs600312.aspx

And as Igor noted, Perl has the same behavior.

Now, the Singleline and Multiline RegexOptions change behavior based around dots and line feeds. You can enable the Singleline RegexOption so that the dot matches line feeds. And you can enable the Multiline RegexOption so that ^ and $ mark the beginning and end of every line (denoted by line feeds). But you can't change the inherent behavior of the dot (.) operator to match everything except for \r\n.