如何仅使用一个Regex将一个字符串替换为另一个字符串，还是必须使用多个Regex和temp字符串？

Question

I have a variable being given a value like this:

vm.WordType = phrase.WordType;

where the value of phrase.WordType can be something like this:

"Godan verb with ru ending, Transitive Verb"

and I would like to change it to

"Godan v with ru end, Transitive v"

I can use Regex to for example replace verb with v but is there a way that I can use Regex to do more replacements, such as replace "ending" with "end" or do I have to somehow string together multiple Regex and use temp variables?

vm.WordType = Regex.Replace(phrase.WordType, "verb", "v", RegexOptions.IgnoreCase);

Answer 1

You could of course just call Regex.Replace 2 times - the first time replacing "verb", the second time replacing "ending".

If you don't like that, you could do it in one single regex like this:

Regex.Replace("Godan verb with ru ending, Transitive Verb", "(v)erb|(end)ing", "$1$2", RegexOptions.IgnoreCase)

The regex I used here is:

(v)erb|(end)ing

It matches either "verb" and puts "v" into group 1, or it matches "ending" and puts "end" into group 2.

The replacement is $1$2 , which means group 1 and group 2.

Let's say you also want to replace "transitive" with "trans", you could easily change the regex to:

(v)erb|(end)ing|(trans)itive

and the replacement to all three groups:

$1$2$3

Note that this approach will preserve case, so "Verb" becomes "V" and "verb" becomes "v". If this is undesirable, you can pass in a MatchEvaluator to convert them to lowercase:

Regex.Replace(
            "Godan verb with ru ending, Transitive Verb", 
            "(v)erb|(end)ing",
            x => string.Join("", x.Groups.Cast<Group>().Skip(1).Select(y => y.Value)).ToLowerInvariant(),
            RegexOptions.IgnoreCase)