I have a piece of code which I am struggling on. I want the onclick function to display the "Question" row in the function but when I place '$questionrow['QuestionContent']' within the brackets, it is giving me an error stating:

Parse error: syntax error, unexpected T_ENCAPSED_AND_WHITESPACE, expecting T_STRING or T_VARIABLE or T_NUM_STRING in /xxx7/Mobile_app/previousquestions.php on line 119

How do I place the QuestionContent within the brackets correctly in function below:

 onclick='parent.addwindow('$questionrow['QuestionContent']');'>Add</button>

Below is whole code:

<?php

$output = "";

        while ($questionrow = mysql_fetch_assoc($questionresult)) {
$output .= "
<table>
      <tr>
<td class='questiontd'>{$questionrow['QuestionContent']}</td>
      <td class='addtd'><button type='button' class='add' onclick='parent.addwindow('$questionrow['QuestionContent']');'>Add</button></td>
      </tr>";
        }
        $output .= "        </table>";

        echo $output;

        ?>