Next text input on different line

Question

I have textbox that I use for diagnostic purposes. The code behind is really simple:

XAML:

<TextBox HorizontalAlignment="Left" Margin="640,20,0,0" TextWrapping="Wrap" Height="280" Width="840" Name="txtDiagnostic" IsHitTestVisible="True" />

C#:

private void AddMessage(string message)
{
    txtDiagnostic.Text += (DateTime.Now.ToString("hh:mm:ss:fff") + " " + message);
}

How can I define that each new input is on a different line? Because right now all errors are in just 1 long line.

14:15:00 Error 1 14:16:00 Error 2 14:17:00 Error 3

Instead of readable with line breaks between each error like this example:

14:15:00 Error 1
14:16:00 Error 2
14:17:00 Error 3

Answer 1

add an Environment.NewLine at the end of each string

txtDiagnostic.Text += (DateTime.Now.ToString("hh:mm:ss:fff") + " " + message) + Environment.NewLine;

and make sure that the textbox is capable of multiline

XAML:

<TextBox
  Name="tbMultiLine"
  TextWrapping="Wrap"
  AcceptsReturn="True"                    <-- IMPORTANT
  VerticalScrollBarVisibility="Visible"   <-- IMPORTANT
>

EDIT: As to respond to the usual string concatination debate you can of course use string.Concat()

String.Concat(txtDiagnostic.Text,DateTime.Now.ToString("hh:mm:ss:fff") , " " , "ERROR....." , Environment.NewLine);

It will be faster. Here is a benchmark code for LINQPad with a 1000 lines:

void Main()
{
    Stopwatch sw = new Stopwatch();

    string text = "";
    sw.Start();
    for (int i = 0; i < 1000; i++)
    {
        //text += (DateTime.Now.ToString("hh:mm:ss:fff") + " " + "ERROR.....") + Environment.NewLine;
        String.Concat(text,DateTime.Now.ToString("hh:mm:ss:fff") , " " , "ERROR....." , Environment.NewLine);
    }
    sw.Stop();
    Console.WriteLine("ELAPSED: " + sw.ElapsedMilliseconds);

}

Output:

+ concatentation took (on my machine) 16 msek
Concat needed 10 msek

Choose yourself, you should know how many error messages you would like to "inform" the user with ;)

Disclaimer: 1000 lines is a very bad benchmark, but I chose it here to fit the use case at hand. Reading more than a 1000 (or even a 1000) lines of error messages is not a software I would like to use. If you start concatenating larger sets of lines (x > 1000) then you really should use the StringBuilder as is also mentioned in the string concatenation debate Link that I provided.

Answer 2

Implementation of Environment.NewLine from the source code:

The implementation in .NET 4.6.1: Source

/*===================================NewLine====================================
**Action: A property which returns the appropriate newline string for the given
**        platform.
**Returns: \r\n on Win32.
**Arguments: None.
**Exceptions: None.
==============================================================================*/
public static String NewLine {
    get {
        Contract.Ensures(Contract.Result<String>() != null);
        return "\r\n";
    }
}

So you could go with \r\n as your last two digits of the string as output text and the result is the exact same as Mong Zhu's answer, since Environment.NewLine is it's implementation.

txtDiagnostic.Text += (DateTime.Now.ToString("hh:mm:ss:fff") + " " + message + "\r\n");

---

It depends on the platform if you either use \n or \r\n. On Windows it is actually \r\n.

From MSDN:

A string containing "\r\n" for non-Unix platforms, or a string containing "\n" for Unix platforms.