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C# Split a string and build a stringarray out of the string [duplicate]

I need to split a string into newlines in .NET and the only way I know of to split strings is with the Split method. However that will not allow me to (easily) split on a newline, so what is the best way to do it?

To split on a string you need to use the overload that takes an array of strings:
string[] lines = theText.Split(
new string[] { Environment.NewLine },
StringSplitOptions.None
);
Edit:
If you want to handle different types of line breaks in a text, you can use the ability to match more than one string. This will correctly split on either type of line break, and preserve empty lines and spacing in the text:
string[] lines = theText.Split(
new string[] { "\r\n", "\r", "\n" },
StringSplitOptions.None
);

What about using a StringReader?
using (System.IO.StringReader reader = new System.IO.StringReader(input)) {
string line = reader.ReadLine();
}

Try to avoid using string.Split for a general solution, because you'll use more memory everywhere you use the function -- the original string, and the split copy, both in memory. Trust me that this can be one hell of a problem when you start to scale -- run a 32-bit batch-processing app processing 100MB documents, and you'll crap out at eight concurrent threads. Not that I've been there before...
Instead, use an iterator like this;
public static IEnumerable<string> SplitToLines(this string input)
{
if (input == null)
{
yield break;
}
using (System.IO.StringReader reader = new System.IO.StringReader(input))
{
string line;
while ((line = reader.ReadLine()) != null)
{
yield return line;
}
}
}
This will allow you to do a more memory efficient loop around your data;
foreach(var line in document.SplitToLines())
{
// one line at a time...
}
Of course, if you want it all in memory, you can do this;
var allTheLines = document.SplitToLines().ToArray();

You should be able to split your string pretty easily, like so:
aString.Split(Environment.NewLine.ToCharArray());

Based on Guffa's answer, in an extension class, use:
public static string[] Lines(this string source) {
return source.Split(new string[] { "\r\n", "\n" }, StringSplitOptions.None);
}

Regex is also an option:
private string[] SplitStringByLineFeed(string inpString)
{
string[] locResult = Regex.Split(inpString, "[\r\n]+");
return locResult;
}

For a string variable s:
s.Split(new string[]{Environment.NewLine},StringSplitOptions.None)
This uses your environment's definition of line endings. On Windows, line endings are CR-LF (carriage return, line feed) or in C#'s escape characters \r\n.
This is a reliable solution, because if you recombine the lines with String.Join, this equals your original string:
var lines = s.Split(new string[]{Environment.NewLine},StringSplitOptions.None);
var reconstituted = String.Join(Environment.NewLine,lines);
Debug.Assert(s==reconstituted);
What not to do:
Use StringSplitOptions.RemoveEmptyEntries, because this will break markup such as Markdown where empty lines have syntactic purpose.
Split on separator new char[]{Environment.NewLine}, because on Windows this will create one empty string element for each new line.

I just thought I would add my two-bits, because the other solutions on this question do not fall into the reusable code classification and are not convenient.
The following block of code extends the string object so that it is available as a natural method when working with strings.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Collections;
using System.Collections.ObjectModel;
namespace System
{
public static class StringExtensions
{
public static string[] Split(this string s, string delimiter, StringSplitOptions options = StringSplitOptions.None)
{
return s.Split(new string[] { delimiter }, options);
}
}
}
You can now use the .Split() function from any string as follows:
string[] result;
// Pass a string, and the delimiter
result = string.Split("My simple string", " ");
// Split an existing string by delimiter only
string foo = "my - string - i - want - split";
result = foo.Split("-");
// You can even pass the split options parameter. When omitted it is
// set to StringSplitOptions.None
result = foo.Split("-", StringSplitOptions.RemoveEmptyEntries);
To split on a newline character, simply pass "\n" or "\r\n" as the delimiter parameter.
Comment: It would be nice if Microsoft implemented this overload.

Starting with .NET 6 we can use the new String.ReplaceLineEndings() method to canonicalize cross-platform line endings, so these days I find this to be the simplest way:
var lines = input
.ReplaceLineEndings()
.Split(Environment.NewLine, StringSplitOptions.None);

I'm currently using this function (based on other answers) in VB.NET:
Private Shared Function SplitLines(text As String) As String()
Return text.Split({Environment.NewLine, vbCrLf, vbLf}, StringSplitOptions.None)
End Function
It tries to split on the platform-local newline first, and then falls back to each possible newline.
I've only needed this inside one class so far. If that changes, I will probably make this Public and move it to a utility class, and maybe even make it an extension method.
Here's how to join the lines back up, for good measure:
Private Shared Function JoinLines(lines As IEnumerable(Of String)) As String
Return String.Join(Environment.NewLine, lines)
End Function

Well, actually split should do:
//Constructing string...
StringBuilder sb = new StringBuilder();
sb.AppendLine("first line");
sb.AppendLine("second line");
sb.AppendLine("third line");
string s = sb.ToString();
Console.WriteLine(s);
//Splitting multiline string into separate lines
string[] splitted = s.Split(new string[] {System.Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries);
// Output (separate lines)
for( int i = 0; i < splitted.Count(); i++ )
{
Console.WriteLine("{0}: {1}", i, splitted[i]);
}

string[] lines = text.Split(
Environment.NewLine.ToCharArray(),
StringSplitOptions.RemoveEmptyStrings);
The RemoveEmptyStrings option will make sure you don't have empty entries due to \n following a \r
(Edit to reflect comments:) Note that it will also discard genuine empty lines in the text. This is usually what I want but it might not be your requirement.

I did not know about Environment.Newline, but I guess this is a very good solution.
My try would have been:
string str = "Test Me\r\nTest Me\nTest Me";
var splitted = str.Split('\n').Select(s => s.Trim()).ToArray();
The additional .Trim removes any \r or \n that might be still present (e. g. when on windows but splitting a string with os x newline characters). Probably not the fastest method though.
EDIT:
As the comments correctly pointed out, this also removes any whitespace at the start of the line or before the new line feed. If you need to preserve that whitespace, use one of the other options.

Examples here are great and helped me with a current "challenge" to split RSA-keys to be presented in a more readable way. Based on Steve Coopers solution:
string Splitstring(string txt, int n = 120, string AddBefore = "", string AddAfterExtra = "")
{
//Spit each string into a n-line length list of strings
var Lines = Enumerable.Range(0, txt.Length / n).Select(i => txt.Substring(i * n, n)).ToList();
//Check if there are any characters left after split, if so add the rest
if(txt.Length > ((txt.Length / n)*n) )
Lines.Add(txt.Substring((txt.Length/n)*n));
//Create return text, with extras
string txtReturn = "";
foreach (string Line in Lines)
txtReturn += AddBefore + Line + AddAfterExtra + Environment.NewLine;
return txtReturn;
}
Presenting a RSA-key with 33 chars width and quotes are then simply
Console.WriteLine(Splitstring(RSAPubKey, 33, "\"", "\""));
Output:
Hopefully someone find it usefull...

Silly answer: write to a temporary file so you can use the venerable
File.ReadLines
var s = "Hello\r\nWorld";
var path = Path.GetTempFileName();
using (var writer = new StreamWriter(path))
{
writer.Write(s);
}
var lines = File.ReadLines(path);

using System.IO;
string textToSplit;
if (textToSplit != null)
{
List<string> lines = new List<string>();
using (StringReader reader = new StringReader(textToSplit))
{
for (string line = reader.ReadLine(); line != null; line = reader.ReadLine())
{
lines.Add(line);
}
}
}

Very easy, actually.
VB.NET:
Private Function SplitOnNewLine(input as String) As String
Return input.Split(Environment.NewLine)
End Function
C#:
string splitOnNewLine(string input)
{
return input.split(environment.newline);
}

How to contact whole text from file into the string avoiding empty lines beetwen strings

How to get whole text from document contacted into the string. I'm trying to split text by dot: string[] words = s.Split('.'); I want take this text from text document. But if my text document contains empty lines between strings, for example:
pat said, “i’ll keep this ring.”
she displayed the silver and jade wedding ring which, in another time track,
she and joe had picked out; this
much of the alternate world she had elected to retain. he wondered what - if any - legal basis she had kept in addition. none, he hoped; wisely, however, he said nothing. better not even to ask.
result looks like this:
1. pat said ill keep this ring
2. she displayed the silver and jade wedding ring which in another time track
3. she and joe had picked out this
4. much of the alternate world she had elected to retain
5. he wondered what if any legal basis she had kept in addition
6. none he hoped wisely however he said nothing
7. better not even to ask
but desired correct output should be like this:
1. pat said ill keep this ring
2. she displayed the silver and jade wedding ring which in another time track she and joe had picked out this much of the alternate world she had elected to retain
3. he wondered what if any legal basis she had kept in addition
4. none he hoped wisely however he said nothing
5. better not even to ask
So to do this first I need to process text file content to get whole text as single string, like this:
pat said, “i’ll keep this ring.” she displayed the silver and jade wedding ring which, in another time track, she and joe had picked out; this much of the alternate world she had elected to retain. he wondered what - if any - legal basis she had kept in addition. none, he hoped; wisely, however, he said nothing. better not even to ask.
I can't to do this same way as it would be with list content for example: string concat = String.Join(" ", text.ToArray());,
I'm not sure how to contact text into string from text document

I think this is what you want:
var fileLocation = #"c:\\myfile.txt";
var stringFromFile = File.ReadAllText(fileLocation);
//replace Environment.NewLine with any new line character your file uses
var withoutNewLines = stringFromFile.Replace(Environment.NewLine, "");
//modify to remove any unwanted character
var withoutUglyCharacters = Regex.Replace(withoutNewLines, "[“’”,;-]", "");
var withoutTwoSpaces = withoutUglyCharacters.Replace(" ", " ");
var result = withoutTwoSpaces.Split('.').Where(i => i != "").Select(i => i.TrimStart()).ToList();
So first you read all text from your file, then you remove all unwanted characters and then split by . and return non empty items

Have you tried replacing double new-lines before splitting using a period?
static string[] GetSentences(string filePath) {
if (!File.Exists(filePath))
throw new FileNotFoundException($"Could not find file { filePath }!");
var lines = string.Join("", File.ReadLines(filePath).Where(line => !string.IsNullOrEmpty(line) && !string.IsNullOrWhiteSpace(line)));
var sentences = Regex.Split(lines, #"\.[\s]{1,}?");
return sentences;
}
I haven't tested this, but it should work.
Explanation:
if (!File.Exists(filePath))
throw new FileNotFoundException($"Could not find file { filePath }!");
Throws an exception if the file could not be found. It is advisory you surround the method call with a try/catch.
var lines = string.Join("", File.ReadLines(filePath).Where(line => !string.IsNullOrEmpty(line) && !string.IsNullOrWhiteSpace(line)));
Creates a string, and ignores any lines which are purely whitespace or empty.
var sentences = Regex.Split(lines, #".[\s]{1,}?");
Creates a string array, where the string is split at every period and whitespace following the period.
E.g:
The string "I came. I saw. I conquered" would become
I came
I saw
I conquered
Update:
Here's the method as a one-liner, if that's your style?
static string[] SplitSentences(string filePath) => File.Exists(filePath) ? Regex.Split(string.Join("", File.ReadLines(filePath).Where(line => !string.IsNullOrEmpty(line) && !string.IsNullOrWhiteSpace(line))), #"") : null;

I would suggest you to iterate through all characters and just check if they are in range of 'a' >= char <= 'z' or if char == ' '. If it matches the condition then add it to the newly created string else check if it is '.' character and if it is then end your line and add another one :
List<string> lines = new List<string>();
string line = string.Empty;
foreach(char c in str)
{
if((char.ToLower(c) >= 'a' && char.ToLower(c) <= 'z') || c == 0x20)
line += c;
else if(c == '.')
{
lines.Add(line.Trim());
line = string.Empty;
}
}
Working online example
Or if you prefer "one-liner"s :
IEnumerable<string> lines = new string(str.Select(c => (char)(((char.ToLower(c) >= 'a' && char.ToLower(c) <= 'z') || c == 0x20) ? c : c == '.' ? '\n' : '\0')).ToArray()).Split('\n').Select(s => s.Trim());

I may be wrong about this. I would think that you may not want to alter the string if you are splitting it. Example, there are double/single quote(s) (“) in part of the string. Removing them may not be desired which brings up the possibly of a question, reading a text file that contains single/double quotes (as your example data text shows) like below:
var stringFromFile = File.ReadAllText(fileLocation);
will not display those characters properly in a text box or the console because the default encoding using the ReadAllText method is UTF8. Example the single/double quotes will display (replacement characters) as diamonds in a text box on a form and will be displayed as a question mark (?) when displayed to the console. To keep the single/double quotes and have them display properly you can get the encoding for the OS’s current ANSI encoding by adding a parameter to the ReadAllText method like below:
string stringFromFile = File.ReadAllText(fileLocation, ASCIIEncoding.Default);
Below is code using a simple split method to .split the string on periods (.) Hope this helps.
private void button1_Click(object sender, EventArgs e) {
string fileLocation = #"C:\YourPath\YourFile.txt";
string stringFromFile = File.ReadAllText(fileLocation, ASCIIEncoding.Default);
string bigString = stringFromFile.Replace(Environment.NewLine, "");
string[] result = bigString.Split('.');
int count = 1;
foreach (string s in result) {
if (s != "") {
textBox1.Text += count + ". " + s.Trim() + Environment.NewLine;
Console.WriteLine(count + ". " + s.Trim());
count++;
}
else {
// period at the end of the string
}
}
}

When using indexof and substring how do i parse the right start and end indexs ? And how do i encode hebrew chars?

I have this code:
string firstTag = "Forums2008/forumPage.aspx?forumId=";
string endTag = "</a>";
index = forums.IndexOf(firstTag, index1);
if (index == -1)
continue;
var secondIndex = forums.IndexOf(endTag, index);
result = forums.Substring(index + firstTag.Length + 12, secondIndex - (index + firstTag.Length - 50));
The string i want to extract from is for example:
הנקה
What i want to get is the word after the title only this: הנקה
And the second problem is that when i'm extracting it i see instead hebrew some gibrish like this: ������

One powerful way to do this is to use Regular Expressions instead of trying to find a starting position and use a substring. Try out this code, and you'll see that it extracts the anchor tag's title:
var input = "הנקה";
var expression = new System.Text.RegularExpressions.Regex(#"title=\""([^\""]+)\""");
var match = expression.Match(input);
if (match.Success) {
Console.WriteLine(match.Groups[1]);
}
else {
Console.WriteLine("not found");
}
And for the curious, here is a version in JavaScript:
var input = 'הנקה';
var expression = new RegExp('title=\"([^\"]+)\"');
var results = expression.exec(input);
if (results) {
document.write(results[1]);
}
else {
document.write("not found");
}

Okay here is the solution using String.Substring() String.Split() and String.IndexOf()
String str = "הנקה"; // <== Assume this is passing string. Yes unusual scape sequence are added
int splitStart = str.IndexOf("title="); // < Where to start splitting
int splitEnd = str.LastIndexOf("</a>"); // < = Where to end
/* What we try to extract is this : title="הנקה">הנקה
* (Given without escape sequence)
*/
String extracted = str.Substring(splitStart, splitEnd - splitStart); // <=Extracting required portion
String[] splitted = extracted.Split('"'); // < = Now split with "
Console.WriteLine(splitted[1]); // <= Try to Out but yes will produce ???? But put a breakpoint here and check the values in split array
Now the problem, here you can see that i have to use escape sequence in an unusual way. You may ignore that since you are simply passing the scanning string.
And this actually works, but you cannot visualize it with the provided Console.WriteLine(splitted[1]);
But if you put a break point and check the extracted split array you can see that text are extracted. you can confirm it with following screenshot

Parse Text File Into Dictionary

I have a text file that has several hundred configuration values. The general format of the configuration data is "Label:Value". Using C# .net, I would like to read these configurations, and use the Values in other portions of the code. My first thought is that I would use a string search to look for the Labels then parse out the values following the labels and add them to a dictionary, but this seems rather tedious considering the number of labels/values that I would have to search for. I am interested to hear some thoughts on a possible architecture to perform this task. I have included a small section of a sample text file that contains some of the labels and values (below). A couple of notes: The Values are not always numeric (as seen in the AUX Serial Number); For whatever reason, the text files were formatted using spaces (\s) rather than tabs (\t). Thanks in advance for any time you spend thinking about this.
Sample Text:
AUX Serial Number: 445P000023 AUX Hardware Rev: 1
Barometric Pressure Slope: -1.452153E-02
Barometric Pressure Intercept: 9.524336E+02

This is a nice little brain tickler. I think this code might be able to point you in the right direction. Keep in mind, this fills a Dictionary<string, string>, so there are no conversions of values into ints or the like. Also, please excuse the mess (and the poor naming conventions). It was a quick write-up based on my train of thought.
Dictionary<string, string> allTheThings = new Dictionary<string, string>();
public void ReadIt()
{
// Open the file into a streamreader
using (System.IO.StreamReader sr = new System.IO.StreamReader("text_path_here.txt"))
{
while (!sr.EndOfStream) // Keep reading until we get to the end
{
string splitMe = sr.ReadLine();
string[] bananaSplits = splitMe.Split(new char[] { ':' }); //Split at the colons
if (bananaSplits.Length < 2) // If we get less than 2 results, discard them
continue;
else if (bananaSplits.Length == 2) // Easy part. If there are 2 results, add them to the dictionary
allTheThings.Add(bananaSplits[0].Trim(), bananaSplits[1].Trim());
else if (bananaSplits.Length > 2)
SplitItGood(splitMe, allTheThings); // Hard part. If there are more than 2 results, use the method below.
}
}
}
public void SplitItGood(string stringInput, Dictionary<string, string> dictInput)
{
StringBuilder sb = new StringBuilder();
List<string> fish = new List<string>(); // This list will hold the keys and values as we find them
bool hasFirstValue = false;
foreach (char c in stringInput) // Iterate through each character in the input
{
if (c != ':') // Keep building the string until we reach a colon
sb.Append(c);
else if (c == ':' && !hasFirstValue)
{
fish.Add(sb.ToString().Trim());
sb.Clear();
hasFirstValue = true;
}
else if (c == ':' && hasFirstValue)
{
// Below, the StringBuilder currently has something like this:
// " 235235 Some Text Here"
// We trim the leading whitespace, then split at the first sign of a double space
string[] bananaSplit = sb.ToString()
.Trim()
.Split(new string[] { " " },
StringSplitOptions.RemoveEmptyEntries);
// Add both results to the list
fish.Add(bananaSplit[0].Trim());
fish.Add(bananaSplit[1].Trim());
sb.Clear();
}
}
fish.Add(sb.ToString().Trim()); // Add the last result to the list
for (int i = 0; i < fish.Count; i += 2)
{
// This for loop assumes that the amount of keys and values added together
// is an even number. If it comes out odd, then one of the lines on the input
// text file wasn't parsed correctly or wasn't generated correctly.
dictInput.Add(fish[i], fish[i + 1]);
}
}

So the only general approach that I can think of, given the format that you're limited to, is to first find the first colon on the line and take everything before it as the label. Skip all whilespace characters until you get to the first non-whitespace character. Take all non-whitespace characters as the value of the label. If there is a colon after the end of that value take everything after the end of the previous value to the colon as the next value and repeat. You'll also probably need to trim whitespace around the labels.
You might be able to capture that meaning with a regex, but it wouldn't likely be a pretty one if you could; I'd avoid it for something this complex unless you're entire development team is very proficient with them.

I would try something like this:
While string contains triple space, replace it with double space.
Replace all ": " and ": " (: with double space) with ":".
Replace all " " (double space) with '\n' (new line).
If line don't contain ':' than skip the line. Else, use string.Split(':'). This way you receive arrays of 2 strings (key and value). Some of them may contain empty characters at the beginning or at the end.
Use string.Trim() to get rid of those empty characters.
Add received key and value to Dictionary.
I am not sure if it solves all your cases but it's a general clue how I would try to do it.
If it works you could think about performance (use StringBuilder instead of string wherever it is possible etc.).

This is probably the dirtiest function I´ve ever written, but it works.
StreamReader reader = new StreamReader("c:/yourFile.txt");
Dictionary<string, string> yourDic = new Dictionary<string, string>();
StreamReader reader = new StreamReader("c:/yourFile.txt");
Dictionary<string, string> yourDic = new Dictionary<string, string>();
while (reader.Peek() >= 0)
{
string line = reader.ReadLine();
string[] data = line.Split(':');
if (line != String.Empty)
{
for (int i = 0; i < data.Length - 1; i++)
{
if (i != 0)
{
bool isPair;
if (i % 2 == 0)
{
isPair = true;
}
else
{
isPair = false;
}
if (isPair)
{
string keyOdd = data[i].Trim();
try { keyOdd = keyOdd.Substring(keyOdd.IndexOf(' ')).TrimStart(); }
catch { }
string valueOdd = data[i + 1].TrimStart();
try { valueOdd = valueOdd.Remove(valueOdd.IndexOf(' ')); } catch{}
yourDic.Add(keyOdd, valueOdd);
}
else
{
string keyPair = data[i].TrimStart();
keyPair = keyPair.Substring(keyPair.IndexOf(' ')).Trim();
string valuePair = data[i + 1].TrimStart();
try { valuePair = valuePair.Remove(valuePair.IndexOf(' ')); } catch { }
yourDic.Add(keyPair, valuePair);
}
}
else
{
string key = data[i].Trim();
string value = data[i + 1].TrimStart();
try { value = value.Remove(value.IndexOf(' ')); } catch{}
yourDic.Add(key, value);
}
}
}
}
How does it works?, well splitting the line you can know what you can get in every position of the array, so I just play with the even and odd values.
You will understand me when you debug this function :D. It fills the Dictionary that you need.

I have another idea. Does values contain spaces? If not you could do like this:
Ignore white spaces until you read some other char (first char of key).
Read string until ':' occures.
Trim key that you get.
Ignore white spaces until you read some other char (first char of value).
Read until you get empty char.
Trim value that you get.
If it is the end than stop. Else, go back to step 1.
Good luck.

Maybe something like this would work, be careful with the ':' character
StreamReader reader = new StreamReader("c:/yourFile.txt");
Dictionary<string, string> yourDic = new Dictionary<string, string>();
while (reader.Peek() >= 0)
{
string line = reader.ReadLine();
yourDic.Add(line.Split(':')[0], line.Split(':')[1]);
}
Anyway, I recommend to organize that file in some way that you´ll always know in what format it comes.

How to split a string while preserving line endings?

I have a block of text and I want to get its lines without losing the \r and \n at the end. Right now, I have the following (suboptimal code):
string[] lines = tbIn.Text.Split('\n')
.Select(t => t.Replace("\r", "\r\n")).ToArray();
So I'm wondering - is there a better way to do it?
Accepted answer
string[] lines = Regex.Split(tbIn.Text, #"(?<=\r\n)(?!$)");

The following seems to do the job:
string[] lines = Regex.Split(tbIn.Text, #"(?<=\r\n)(?!$)");
(?<=\r\n) uses 'positive lookbehind' to match after \r\n without consuming it.
(?!$) uses negative lookahead to prevent matching at the end of the input and so avoids a final line that is just an empty string.

Something along the lines of using this regular expression:
[^\n\r]*\r\n
Then use Regex.Matches().
The problem is you need Group(1) out of each match and create your string list from that. In Python you'd just use the map() function. Not sure the best way to do it in .NET, you take it from there ;-)

Dmitri, your solution is actually pretty compact and straightforward. The only thing more efficient would be to keep the string-splitting characters in the generated array, but the APIs simply don't allow for that. As a result, every solution will require iterating over the array and performing some kind of modification (which in C# means allocating new strings every time). I think the best you can hope for is to not re-create the array:
string[] lines = tbIn.Text.Split('\n');
for (int i = 0; i < lines.Length; ++i)
{
lines[i] = lines[i].Replace("\r", "\r\n");
}
... but as you can see that looks a lot more cumbersome! If performance matters, this may be a bit better. If it really matters, you should consider manually parsing the string by using IndexOf() to find the '\r's one at a time, and then create the array yourself. This is significantly more code, though, and probably not necessary.
One of the side effects of both your solution and this one is that you won't get a terminating "\r\n" on the last line if there wasn't one already there in the TextBox. Is this what you expect? What about blank lines... do you expect them to show up in 'lines'?

If you are just going to replace the newline (\n) then do something like this:
string[] lines = tbIn.Text.Split('\n')
.Select(t => t + "\r\n").ToArray();
Edit: Regex.Replace allows you to split on a string.
string[] lines = Regex.Split(tbIn.Text, "\r\n")
.Select(t => t + "\r\n").ToArray();

As always, extension method goodies :)
public static class StringExtensions
{
public static IEnumerable<string> SplitAndKeep(this string s, string seperator)
{
string[] obj = s.Split(new string[] { seperator }, StringSplitOptions.None);
for (int i = 0; i < obj.Length; i++)
{
string result = i == obj.Length - 1 ? obj[i] : obj[i] + seperator;
yield return result;
}
}
}
usage:
string text = "One,Two,Three,Four";
foreach (var s in text.SplitAndKeep(","))
{
Console.WriteLine(s);
}
Output:
One,
Two,
Three,
Four

You can achieve this with a regular expression. Here's an extension method with it:
public static string[] SplitAndKeepDelimiter(this string input, string delimiter)
{
MatchCollection matches = Regex.Matches(input, #"[^" + delimiter + "]+(" + delimiter + "|$)", RegexOptions.Multiline);
string[] result = new string[matches.Count];
for (int i = 0; i < matches.Count ; i++)
{
result[i] = matches[i].Value;
}
return result;
}
I'm not sure if this is a better solution. Yours is very compact and simple.