title: CodeIgniter: Fatal error: Can't use method return value in write context
body: <p>I have this issue where I am posting a response into the controller, however it throws this error. This is the first time I am coming across this error.</p>
  
  <p>Kindly find the code below:</p>
  
  <pre><code>    if (isset($this-&gt;input-&gt;post('responseCode'))) 
         {
           echo '&lt;p&gt;&lt;strong&gt;Cardstream Response&lt;/strong&gt;&lt;/p&gt;';
           echo '&lt;pre&gt;';
           print_r($this-&gt;input-&gt;post());
           echo '&lt;/pre&gt;';
         }
  </code></pre>
  
  <p>It is pointing at this particular line <code>if (isset($this-&gt;input-&gt;post('responseCode')))</code></p>
  
  <p>This is a cardstream integration. Unfortunately I haven't found the library for cardstream in codeigniter, hence I am using the Core PHP code for the same.</p>
  
  <p>Any help will be greatly appreciated. Thanks.</p>