C# Regex - Remove extra whitespaces but keep new l

问题:

This question already has an answer here:

• Match whitespace but not newlines 6 answers

I am using this regex :

Regex.Replace(value.Trim(), @"\s+", " ");

To trim and minimize extra spaces into one space.
The problem is that it also removes new lines from the text.

How can I fix the regex so that it will keep the new lines ?

回答1:

Exclude CRLF's [^\S\r\n]+ within the whitespace class.
[^] is a negative class. \S is a negative class which equals not [ space, tab, ff, lf, cr ]

The thing about negative classes is it factored out of the group and applies to each member
in the group separately. And like math two negative equal a positive.

Not Not whitespace = [^\S] = [\s]

However, the negative condition applies to the next class item as well as the next ...

So, now that whitespace is included, you can exclude particular whitespace items from the class.
[^\S\r\n] means all whitespace except CR or LF.

回答2:

Haven't managed to test it in C# yet, but the following works on http://www.regexr.com/:

Regex.Replace(value.Trim(), @"[^\S\r\n]+", " ");

Credit goes to Match whitespace but not newlines

The Regex works by matching the negated character class of not-whitespace or return / newlines.