title: PHP string replace match whole word
body: <p>I would like to replace just complete words using php</p>
  
  <p>Example :
  If I have </p>
  
  <pre><code>$text = "Hello hellol hello, Helloz";
  </code></pre>
  
  <p>and I use</p>
  
  <pre><code>$newtext = str_replace("Hello",'NEW',$text);
  </code></pre>
  
  <p>The new text should look like</p>
  
  <blockquote>
    <p>NEW hello1 hello, Helloz</p>
  </blockquote>
  
  <p>PHP returns</p>
  
  <blockquote>
    <p>NEW hello1 hello, NEWz</p>
  </blockquote>
  
  <p>Thanks.</p>