title: How can I use the value of a variable as constant?
body: <ol>
  <li><p>I have a PHP site which uses language system based on "define" method.
  For example:</p>
  
  <pre><code>define("_question_1", "How old are you?");
  define("_question_2", "Question 2?");
  define("_question_3", "Question 3?");
  ....
  define("_question_10", "Question 10?");
  </code></pre></li>
  <li><p>I have 5-10 questions I need to ask. And I need to select what question I want to ask. So I make a query to my DB. Something like:</p>
  
  <pre><code>SELECT q_title FROM questions_db WHERE id=3 OR id=10;
  </code></pre>
  
  <p>Database returns two TEXT(!) values:</p>
  
  <pre><code>_question_3, _question_10
  </code></pre>
  
  <p>Which I save to:</p>
  
  <pre><code>$a = _question_3; 
  $b = _question_10;
  </code></pre></li>
  <li><p>Next thing I need is to show the text of the description defined earlier. When I use _question_3 as VARIABLE it works like this:</p>
  
  <pre><code>echo ""._question_3.""; //returns "Question 3?"
  </code></pre>
  
  <p>But I have only _question_3 as TEXT value and it's works like this:</p>
  
  <pre><code>echo "".$a.""; //returns "_question_3"
  </code></pre></li>
  </ol>
  
  <p>THE QUESTION: How to convert text value to PHP variable and make something like?</p>
  
  <pre><code>    define("_question_3", "Question 3?");
      $a = _question_3; //text value
      //do something with $a.... 
      echo "".$a.""; //returns "Question 3?"
  </code></pre>
  
  <p>Thanks for help.
  P.S. Please change the title if it doesn't clear to understanding.</p>