Splitting of a string using Regex

Question

I have string of the following format:

string test = "test.BO.ID";

My aim is string that part of the string whatever comes after first dot. So ideally I am expecting output as "BO.ID".

Here is what I have tried:

// Checking for the first occurence and take whatever comes after dot
var output = Regex.Match(test, @"^(?=.).*?");

The output I am getting is empty.

What is the modification I need to make it for Regex?

Wiktor Stribiżew · Accepted Answer · 2016-10-14 12:05:33Z

4

You get an empty output because the pattern you have can match an empty string at the start of a string, and that is enough since .*? is a lazy subpattern and . matches any char.

Use (the value will be in Match.Groups[1].Value)

\.(.*)

or (with a lookahead, to get the string as a Match.Value)

(?<=\.).*

See the regex demo and a C# online demo.

A non-regex approach can be use String#Split with count argument (demo):

var s = "test.BO.ID";
var res = s.Split(new[] {"."}, 2, StringSplitOptions.None);
if (res.GetLength(0) > 1)
    Console.WriteLine(res[1]);

edited Oct 14, 2016 at 12:05

answered Oct 14, 2016 at 11:59

Wiktor Stribiżew

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Comments

Dawnkeeper · Accepted Answer · 2016-10-14 12:00:25Z

3

If you only want the part after the first dot you don't need a regex at all:

x.Substring(x.IndexOf('.'))

answered Oct 14, 2016 at 12:00

Dawnkeeper

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