How do I match the last character in an arbitrary string using C# Regexes?

Question

The obvious attempt is:

Regex.Replace(input, @".$", "X", RegexOptions.Singleline);

This doesn't always work though. Consider the string \r\n\r\n - the above produces the surprising result of \r\nXX. One might expect from reading MSDN (under Multiline) that $ should match just at the end of the entire string, but apparently $ actually means "match at end of string or at the \n just before the end of string".

What might be a correct way to match the last character of an arbitrary string?

Why REGEX?!? WHY!!!! Just split on \r\n and iterate the lines, getting the last character. Regex is not the solution for everything. — C. Ross
– C. Ross, Commented Nov 18, 2009 at 2:51
There's more involved than just matching the last character. Of course if I wanted just the last character then I'd just go input[input.Length - 1]... No splitting of any kind required. — Roman Starkov
– Roman Starkov, Commented Nov 18, 2009 at 2:53

Timwi · Accepted Answer · 2009-11-18 03:00:42Z

8

.NET supports the \z token, which always matches the end of the string:

Regex.Replace(input, @".\z", "X", RegexOptions.Singleline);

answered Nov 18, 2009 at 3:00

Timwi

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Fellmeister Over a year ago

I've got a CLR Assembly using .Net regex and this is perfect for what I need it to do. Thanks.

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