title: Seperate Space delimited word and remove duplicate words
body: <p>I found <strong>preg_split</strong> and <strong>explode</strong> functions in php for breaking space seperated string into words. its quite useful too. but the next step i would like to work is remove the duplicate words and [",","." and few other punctuation marks ] too...</p>
  
  <p>like if<br>
  "<strong>I love nepal. Nepal is a landlocked country. Nepal is in Asia.</strong>"</p>
  
  <p>I would like to get only unique words in the sentance like:<br>
  <strong>I, love, nepal, is, a, landlocked, country, in, Asia</strong>  </p>