title: regex to find url in a text
body: <p>I have to find the first url in the text with a regular expression:</p>
  
  <p>for example:</p>
  
  <pre><code>I love this website:http://www.youtube.com/music it's fantastic
  </code></pre>
  
  <p>or</p>
  
  <pre><code>[ es. http://www.youtube.com/music] text
  </code></pre>