title: How to rearrange characters in a string?
body: <p>I have a string like this:</p>
  
  <pre><code>1a2b3c4d5e6f7g8h
  </code></pre>
  
  <p>And I need to rearrange it as follow:</p>
  
  <pre><code>a1b2c3d4e5f6g7h8
  </code></pre>
  
  <p>Do you understand what I mean? For each two characters, the numerical character swapping place with the following letter, i.e. from <code>1a</code> change it to <code>a1</code></p>
  
  <p>So my question is <strong>how to rearrange the numerical characters and letters in the string</strong>? My string always has the said pattern, i.e. one integer then followed by a letter then followed by a integer then followed by a letter and so on.</p>