How can I quickly split a long string into serval ones by the line terminator ("\r\n")?

Does this help?

using System;
using System.Text.RegularExpressions;

class Program
{
    static void Main()
    {
    string value = "cat\r\ndog\r\nanimal\r\nperson";
    //
    // Split the string on line breaks.
    // ... The return value from Split is a string[] array.
    //
    string[] lines = Regex.Split(value, "\r\n");

    foreach (string line in lines)
    {
        Console.WriteLine(line);
    }
    }
}

Also check this page out:
http://www.dotnetperls.com/split[^]

Cheers

The Solution 2 is very good.

But, if there are empty spaces, I think they may not be deleted.

void Main()
    {
    string input= "First Line\r\nSecond Line\r\n\r\nThird Line";
    string[] lines = input.Split(new string[]{"\r\n"},
                    StringSplitOptions.RemoveEmptyEntries);
    foreach (string line in lines)
    {
        Console.WriteLine (line);
    }
}
//First Line
//Second Line
//Third Line

In the sample shown above after SecondLine there is an empty entry due to repition of \r\n. With StringSplitOptions.RemoveEmptyEntries option this empty entry can removed.

It's not too dificult to do that.
It does depend however how you want to split it up...

Here's an example of either 2 ways i think would suit your problem:

int charsToSplit = 9;
string strng = "teststring that is quite long. When do you want to cut it up?"

strng.Insert(charsToSplit, "/r/n"); // this, you could use to cut the string after a number of characters

strng.Replace(".", "./r/n");//this, you could use if you want a linebreak after every point-character

hope this helps you! ;)