title: regex to fetch string between [a] and [/a] excluding any other tag like [b][/b] that comes in between
body: <p>I have an input like the following</p>
  
  <pre><code>[a href=http://twitter.com/suddentwilight][font][b][i]@suddentwilight[/font][/a] My POV: Rakhi Sawant hits below the belt &amp;amp; does anything for attention... [a href=http://twitter.com/mallikaLA][b]http://www.test.com[/b][/a] has maintained the grace/decency :)
  </code></pre>
  
  <p>Now I need to get the string <code>@suddentwilight</code> and <code>http://www.test.com</code> that comes inside the anchor tags. there might be some [b] or [i] like tags wrapping the actual text. I need to ignore that.</p>
  
  <p>Basically I need to get a string matching that starts with <code>[a]</code> then need to get the string/url before closing of the a tag <code>[/a]</code>.</p>
  
  <p>Please Suggest</p>