Split a string with delimiters but keep the delimiters in the result in C#

Question

I would like to split a string with delimiters but keep the delimiters in the result.

How would I do this in C#?

Answer 1

If the split chars were ,, ., and ;, I'd try:

using System.Text.RegularExpressions; ...     string[] parts = Regex.Split(originalString, @"(?<=[.,;])") 

(?<=PATTERN) is positive look-behind for PATTERN. It should match at any place where the preceding text fits PATTERN so there should be a match (and a split) after each occurrence of any of the characters.

Answer 2

If you want the delimiter to be its "own split", you can use Regex.Split e.g.:

string input = "plum-pear"; string pattern = "(-)";  string[] substrings = Regex.Split(input, pattern);    // Split on hyphens foreach (string match in substrings) {    Console.WriteLine("'{0}'", match); } // The method writes the following to the console: //    'plum' //    '-' //    'pear' 

So if you are looking for splitting a mathematical formula, you can use the following Regex

@"([*()\^\/]|(?<!E)[\+\-])"  

This will ensure you can also use constants like 1E-02 and avoid having them split into 1E, - and 02

So:

Regex.Split("10E-02*x+sin(x)^2", @"([*()\^\/]|(?<!E)[\+\-])") 

Yields:

• 10E-02
• *
• x
• +
• sin
• (
• x
• )
• ^
• 2