What is the easiest way in C# to trim a newline off of a string?

The following works for me.

sb.ToString().TrimEnd( '\r', '\n' );

or

sb.ToString().TrimEnd( Environment.NewLine.ToCharArray());

How about:

public static string TrimNewLines(string text)
{
    while (text.EndsWith(Environment.NewLine))
    {
        text = text.Substring(0, text.Length - Environment.NewLine.Length);
    }
    return text;
}

It's somewhat inefficient if there are multiple newlines, but it'll work.

Alternatively, if you don't mind it trimming (say) "\r\r\r\r" or "\n\n\n\n" rather than just "\r\n\r\n\r\n":

// No need to create a new array each time
private static readonly char[] NewLineChars = Environment.NewLine.ToCharArray();

public static string TrimNewLines(string text)
{
    return text.TrimEnd(NewLineChars);
}

Use the Framework. The ReadLine() method has the following to say:

A line is defined as a sequence of characters followed by a line feed ("\n"), a carriage return ("\r") or a carriage return immediately followed by a line feed ("\r\n"). The string that is returned does not contain the terminating carriage return or line feed.

So the following will do the trick

_content = new StringReader(sb.ToString()).ReadLine();

What about

_content = sb.ToString().Trim(Environment.NewLine.ToCharArray());

_content = sb.TrimEnd(Environment.NewLine.ToCharArray());

This will of course remove "\r\r\r\r" as well as "\n\n\n\n" and other combinations. And in "enviroments" where NewLine is other than "\n\r" you might get some strange behaviors :-)

But if you can live with this then I belive this is the most effectiv way to remove new line characters at the end of a string.

How about just:

string text = sb.ToString().TrimEnd(null)

That will pull all whitespace characters from the end of the string -- only a problem if you wanted to preserve non-newline whitespace.

Somewhat of a non-answer, but the easiest way to trim a newline off of a string is to not have the newline on the string in the first place, by making sure it is is never seen by your own code. That is, by using native functions which remove the newline. Many stream and file/io methods will not include the newline if you ask for output line by line, though it may be necessary to wrap something in a System.IO.BufferedStream.

Things like System.IO.File.ReadAllLines can be used in place of System.IO.File.ReadAllText most of the time, and ReadLine can be used instead of Read once you are working with the right type of stream (e.g. BufferedStream).