title: Add one space after every two characters and add a character infront of every single character
body: <p>I want to add one space after every two characters, and add a character in front of every single character.</p>
  
  <p>This is my code:</p>
  
  <pre><code>string str2;
  str2 = str1.ToCharArray().Aggregate("", (result, c) =&gt; result += ((!string.IsNullOrEmpty(result) &amp;&amp; (result.Length + 1) % 3 == 0) ? " " : "") + c.ToString());
  </code></pre>
  
  <p>I have no problems separating every two characters with one space, but how do I know if the separated string has an individual character, and add a character infront of that character?</p>
  
  <p>I understand that my question is confusing as I'm not sure how to put what I want in words..
  So I'll just give an example:</p>
  
  <p>I have this string:</p>
  
  <pre><code>0123457
  </code></pre>
  
  <p>After separating every two characters with a space, I'll get:</p>
  
  <pre><code>01 23 45 7
  </code></pre>
  
  <p>I want to add a 6 infront of the 7.</p>
  
  <p>Note: Numbers are dependent on user's input, so it's not always the same.</p>
  
  <p>Thanks.</p>