title: How to add a suffix at the end of a string in PHP
body: <p>I am trying to add a .html suffix at the end of all strings supplied by the user before it is entered into the database. Here's my code so far:</p>
  
  <pre><code>strtolower(str_replace(" ", "_", $postTitle));
  </code></pre>
  
  <p>The above takes the title of the post the user it trying to make, turns it to lower case, replaces all white spaces with underscores and makes it ready to be entered into a database column called post_url.</p>
  
  <p>I just need it to do one more thing and that's to add a .html at the end of each post url. What is the function to do this?</p>