Adding new line of data to TextBox

If you use WinForms:

Use the AppendText(myTxt) method on the TextBox instead (.net 3.5+):

    private void button1_Click(object sender, EventArgs e)
    {
        string sent = chatBox.Text;

        displayBox.AppendText(sent);
        displayBox.AppendText(Environment.NewLine);

    }

Text in itself has typically a low memory footprint (you can say a lot within f.ex. 10kb which is "nothing"). The TextBox does not render all text that is in the buffer, only the visible part so you don't need to worry too much about lag. The slower operations are inserting text. Appending text is relatively fast.

If you need a more complex handling of the content you can use StringBuilder combined with the textbox. This will give you a very efficient way of handling text.

Following are the ways

1. From the code (the way you have mentioned) ->

   displayBox.Text += sent + "\r\n";
   

   or

   displayBox.Text += sent + Environment.NewLine;
   

2. From the UI
   a) WPF

   Set TextWrapping="Wrap" and AcceptsReturn="True"   
   

   Press Enter key to the textbox and new line will be created

   b) Winform text box

   Set TextBox.MultiLine and TextBox.AcceptsReturn to true
   

I find this method saves a lot of typing, and prevents a lot of typos.

string nl = "\r\n";

txtOutput.Text = "First line" + nl + "Second line" + nl + "Third line";