title: c# replace "\n" text with newline in a textbox
body: <p>I have some text (for example "o\nour first place, and this\n\n13") and I want that for each "\n" string founded into the text this must be replaced with newline...</p>
  
  <p>output for the example will be:</p>
  
  <p>o
  our first place, and this</p>
  
  <p>13
  How can I make? textbox is multiline</p>
  
  <p>the code is</p>
  
  <pre><code>string text_str = txtbox.Text;
  text_str .Replace("(?&lt;!\r)\n", "\r\n");
  txtbox.Clear();
  txtbox.Text = text_str;
  </code></pre>