title: How to pass selected option to another page
body: <p>while I'm working with a Select Tag, nothing is displayed as can not be seen in the second page using $_SESSION variables. Someone helps me: I'm so confused:
  My first page:</p>
  
  <pre><code>  &lt;?php
      session_start();
      if(isset($_SESSION['a'])){
          echo $_SESSION['a'];
      }
      ?&gt;
      &lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
      &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
      &lt;head&gt;
      &lt;meta http-equiv="Content-Type" content="text/html; charset=utf-8" /&gt;
      &lt;title&gt;Untitled Document&lt;/title&gt;
      &lt;/head&gt;
  
      &lt;body&gt;
      &lt;form id="form1" name="form1" method="post" action="test2.php"&gt;
        &lt;label for="df"&gt;&lt;/label&gt;
        &lt;input type="text" name="df" id="df" /&gt;
        &lt;select name="a"&gt;
        &lt;option value="12" /&gt;12
  
        &lt;option value="13"/&gt;13
  
        &lt;/select&gt;
        &lt;input type="submit" value="send" /&gt;
      &lt;/form&gt;
      &lt;?php
      if(isset($_post)){
          if(isset($_POST['a'])){
      $_SESSION['a']= $_POST['a'];
      }
      }
      ?&gt;
      &lt;/body&gt;
      &lt;/html&gt;
  </code></pre>
  
  <p>My second Page:</p>
  
  <pre><code> &lt;?php
      session_start();
      $r12=13;
      if(isset($_SESSION['a'])){
          echo $r12;
      }
  
      ?&gt;
      &lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;
      &lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
      &lt;head&gt;
      &lt;meta http-equiv="Content-Type" content="text/html; charset=utf-8" /&gt;
      &lt;title&gt;Untitled Document&lt;/title&gt;
      &lt;/head&gt;
  
      &lt;body&gt;
  
      aaa
      &lt;?php
  
      if(isset($_SESSION['a'])){
          echo $_SESSION['a'];
      }
      ?&gt;
      &lt;/body&gt;
      &lt;/html&gt;
  </code></pre>