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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);
}

read specific websourcecode in c#

When I press a button the following happens:
HttpWebRequest request = (HttpWebRequest)WebRequest
.Create("http://oldschool.runescape.com/slu");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
StreamReader sr = new StreamReader(response.GetResponseStream());
richTextBox1.Text = sr.ReadToEnd();
sr.Close();
In short the data gets transferred to my textbox (this works perfectly)
Now if I choose world 78 (for example, from a combobox, it will refer to the last digits of that line) I want to get the value 968, if i choose world 14, I want to get the value 973.
This is an example of the printed data
e(378,true,0,"oldschool78",968,"United States","US","Old School 78");
e(314,true,0,"oldschool14",973,"United States","US","Old School 14");
What can I use to read this?

So there are two problems here, the first is selecting the right line, then getting the number out.
First you want a method for getting each of the lines in to a list, eg using something like this:
List<String> lines = new List<String>()
string line = sr.ReadLine();
while(line != null)
{
lines.Add(line);
line = sr.ReadLine(); // read the next line
}
Then you need to find the relevant line and get the token out of it.
Probably the most simple way is, for each line, split the string up by ',', '\"', '(' and ')' (using
String.Split). Ie, we get basically the parameters.
Eg
foreach(string lineInFile in lines)
{
// split the string in to tokens
string[] tokens = lineInFile.Split(',', '\"', '(', ')');
// based on the sample strings and how we've split this,
// we take the 15th entry
string endParameter = tokens[15]; //endParamter = "Old School 14"
...
We now use a regular expression to extract the number. The pattern we will use is d+, ie 1 or more digits.
Regex numberFinder = new Regex("\\d+");
Match numberMatch = numberFinder.Match(endParameter);
// we assume that there is a match, because if there isn't the string isn't
// correct, you should do some error handling here
string matchedNumber = numberMatch.Value;
int value = Int32.Parse(matchedValue); // we convert the string in to the number
if(value == desiredValue)
...
We check if the value matches the value we were looking for (eg 14), we now need to get the number you wanted.
We've already split the parameters, and the number we want is the 8th item (eg index 7 in string[] tokens). Since, at least in your example, this is just a lone number, we can just parse this to get the int.
{
return Int32.Parse(tokens[7]);
}
}
Again here we are assuming that the string is in the formats you showed, and you should do error protection here to.

split a string from a text file into another list

Hi i know the Title might sound a little confusing but im reading in a text file with many lines of data
Example
12345 Test
34567 Test2
i read in the text 1 line at a time and add to a list
using (StreamReader reader = new StreamReader("Test.txt"))
{
string line;
while ((line = reader.ReadLine()) != null)
{
list.Add(line);
}
}
how do i then separate the 1234 from the test so i can pull only the first column of data if i need like list(1).pars[1] would be 12345 and list(2).pars[2] would be test2
i know this sounds foggy but i hope someone out there understands

Maybe something like this:
string test="12345 Test";
var ls= test.Split(' ');
This will get you a array of string. You can get them with ls[0] and ls[1].
If you just what the 12345 then ls[0] is the one to choose.

If you're ok with having a list of string[]'s you can simply do this:
var list = new List<string[]>();
using (StreamReader reader = new StreamReader("Test.txt"))
{
string line;
while ((line = reader.ReadLine()) != null)
{
list.Add(line.Split(' '));
}
}
string firstWord = list[0][0]; //12345
string secondWord = list[0][1]; //Test

When you have a string of text you can use the Split() method to split it in many parts. If you're sure every word (separated by one or more spaces) is a column you can simply write:
string[] columns = line.Split(' ');
There are several overloads of that function, you can specify if blank fields are skipped (you may have, for example columns[1] empty in a line composed by 2 words but separated by two spaces). If you're sure about the number of columns you can fix that limit too (so if any text after the last column will be treated as a single field).
In your case (add to the list only the first column) you may write:
if (String.IsNullOrWhiteSpace(line))
continue;
string[] columns = line.TrimLeft().Split(new char[] { ' ' }, 2);
list.Add(columns[0]);
First check is to skip empty or lines composed just of spaces. The TrimLeft() is to remove spaces from beginning of the line (if any). The first column can't be empty (because the TrimLeft() so yo do not even need to use StringSplitOptions.RemoveEmptyEntries with an additional if (columns.Length > 1). Finally, if the file is small enough you can read it in memory with a single call to File.ReadAllLines() and simplify everything with a little of LINQ:
list.Add(
File.ReadAllLines("test.txt")
.Where(x => !String.IsNullOrWhiteSpace(x))
.Select(x => x.TrimLeft().Split(new char[] { ' ' }, 2)[0]));
Note that with the first parameter you can specify more than one valid separator.

When you have multiple spaces
Regex r = new Regex(" +");
string [] splitString = r.Split(stringWithMultipleSpaces);

var splitted = System.IO.File.ReadAllLines("Test.txt")
.Select(line => line.Split(' ')).ToArray();
var list1 = splitted.Select(split_line => split_line[0]).ToArray();
var list2 = splitted.Select(split_line => split_line[1]).ToArray();

C# StreamReader save to Array with separator

I´ve got a text file with tabulator separated data. What I need in my C# application is that I read one line from the text file and save them to an array, separate them at the each \t. Then I do the same thing with the next row.
My code:
StreamReader sr = new StreamReader(dlg.FileName);
string s = sr.ReadLine();
Now, I already tried to write the line into an array but that doesn´t work. Does anyone one how to manage this?

Use the Split method to create an Array of the line
string[] parts = s.Split('\t');
See Documentation on Split() here

foreach (string line in System.IO.File.ReadAllLines(dlg.FileName))
{
var myArray = line.Split('\t');
}

s.Split('\t') will split your string by the tabulator character, and create a string[] with appropriate length.

Ammending your example code:
StreamReader sr = new StreamReader(dlg.FileName);
string s = sr.ReadLine();
var items = s.Split('\t');
In the end, items contains an array of strings that represent the characters between the tabs. The tabs are not included in the array. The array may contain empty elements (for the case of two consecutive tabs).

Use the String.Split() method: http://msdn.microsoft.com/en-us/library/b873y76a.aspx

StreamReader reader = new StreamReader("input.txt");
string[] content = reader.ReadToEnd().Replace("\n","").Split('\t');
if you want to keep New Line's than
string[] content = reader.ReadToEnd().Split('\t');

In the example below, items will be a String[] containing each line of text's values. It will be overwritten with each iteration so you'll want to do something with it inside the loop. Save it to a larger collection, write it to a file, etc...
StreamReader sr = new StreamReader(dlg.FileName);
while (sr.Peek() >= 0) {
var line = sr.ReadLine();
var items = line.Split(new Char[] { '\t' });
}

If the file contains only one line, then use:
string[] myArray = s.Split('\t');

How would you split by \r\n if String.Split(String[]) did not exist?

Using the .NET MicroFramework which is a really cut-down version of C#. For instance, System.String barely has any of the goodies that we've enjoyed over the years.
I need to split a text document into lines, which means splitting by \r\n. However, String.Split only provides a split by char, not by string.
How can I split a document into lines in an efficient manner (e.g. not looping madly across each char in the doc)?
P.S. System.String is also missing a Replace method, so that won't work.
P.P.S. Regex is not part of the MicroFramework either.

You can do
string[] lines = doc.Split('\n');
for (int i = 0; i < lines.Length; i+= 1)
lines[i] = lines[i].Trim();
Assuming that the µF supports Trim() at all. Trim() will remove all whitespace, that might be useful. Otherwise use TrimEnd('\r')

I would loop across each char in the document, because that's clearly required. How do you think String.Split works? I would try to do so only hitting each character once, however.
Keep a list of strings found so far. Use IndexOf repeatedly, passing in the current offset into the string (i.e. the previous match + 2).

How can I split a document into lines in an efficient manner (e.g. not looping madly across each char in the doc)?
How do you think the built-in Split works?
Just reimplement it yourself as an extension method.

What about:
string path = "yourfile.txt";
string[] lines = File.ReadAllLines(path);
Or
string content = File.ReadAllText(path);
string[] lines = content.Split(
Environment.NewLine.ToCharArray(),
StringSplitOptions.RemoveEmptyEntries);
Readind that .NET Micro Framework 3.0, this code can work:
string line = String.Empty;
StreamReader reader = new StreamReader(path);
while ((line = reader.ReadLine()) != null)
{
// do stuff
}

This may help in some scenario:
StreamReader reader = new StreamReader(file);
string _Line = reader.ReadToEnd();
string IntMediateLine = string.Empty;
IntMediateLine = _Line.Replace("entersign", "");
string[] ArrayLineSpliter = IntMediateLine.Split('any specail chaarater');

If you'd like a MicroFramework compatible split function that works for an entire string of characters, here's one that does the trick, similar to the regular frameworks' version using StringSplitOptions.None:
private static string[] Split(string s, string delim)
{
if (s == null) throw new NullReferenceException();
// Declarations
var strings = new ArrayList();
var start = 0;
// Tokenize
if (delim != null && delim != "")
{
int i;
while ((i = s.IndexOf(delim, start)) != -1)
{
strings.Add(s.Substring(start, i - start));
start = i + delim.Length;
}
}
// Append left over
strings.Add(s.Substring(start));
return (string[]) strings.ToArray(typeof(string));
}

You can split your string with a substring.
String.Split(new string[] { "\r\n" }, StringSplitOptions.None);