CODEWITHSUNDEEP
c#regexstringtext
MDL
MDL

Reputation: 271

Regular expression to get text after underscore which is used as a delimiter

I have a string like this:

So basically i need a regular expression to get those 4 numeric values after the _ delimiter. I'm sure it's super simply but Regex looks like a foreign language to me!

Upvotes: 0

Views: 4826

Answers (2)

Regexident
Regexident

Reputation: 29562

That would be this regular expression:

_([0-9]+)

(Capture group 1 holds the number.)

Or if your engine supports lookbehinds (which as far as I remember is not the case for C#):

(?<=_)[0-9]+

(Capture group 0 holds the number.)

The (...) denotes a catch group. In your match object you can then either access them by their index via yourMatch.Groups[index].Value or if you named your catch groups via (?<name>...) by their name like yourMatch.Groups[name].Value. The value will then hold whatever was matched by that particular group's sub-expression (in your case the 4-digit number).

Also if you only want the regex to match if those are exactly 4 numeric characters,
then replace the + with {4}\b

Edit: As Alan Moore correctly pointed out those are called "capture group", not "catch group". I need more sleep.

Upvotes: 4

cwharris
cwharris

Reputation: 18125

Regex: _(?<number>[0-9]+)

var match = new Regex("_(?<number>[0-9]+)").Match("blah blah blah_0123");

if(match.Success)
{
    var value = match.Groups["number"].Value;
    var number = Int.Parse(value);

    Console.WriteLine(value);  // this will write "0123"
    Console.WriteLine(number); // this will write "123"
}

Upvotes: 2

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