title: Getting an uncaught exception in PHP when trying to get data from POST API
body: <p>I'm trying to access a list of most recent comments on Stack Overflow using this PHP:</p>
  
  <pre><code>&lt;?php
      function do_post_request($url, $data, $optional_headers = null)
      {
        $params = array('http' =&gt; array(
                    'method' =&gt; 'POST',
                    'content' =&gt; $data
                  ));
        if ($optional_headers !== null) {
          $params['http']['header'] = $optional_headers;
        }
        $ctx = stream_context_create($params);
        $fp = @fopen($url, 'rb', false, $ctx);
        if (!$fp) {
          throw new Exception("Problem with $url, $php_errormsg");
        }
        $response = @stream_get_contents($fp);
        if ($response === false) {
          throw new Exception("Problem reading data from $url, $php_errormsg");
        }
        return $response;
      }
      echo do_post_request("https://api.stackexchange.com/2.1/comments?order=desc&amp;sort=creation&amp;site=stackoverflow", "");
  ?&gt;
  </code></pre>
  
  <p>However, when I run it, I get this error message:</p>
  
  <pre><code>$ php index.php 
  
  PHP Notice:  Undefined variable: php_errormsg in /var/www/secomments/index.php on line 14
  PHP Fatal error:  Uncaught exception 'Exception' with message 'Problem with https://api.stackexchange.com/2.1/comments?order=desc&amp;sort=creation&amp;site=stackoverflow, ' in /var/www/secomments/index.php:14
  Stack trace:
  #0 /var/www/secomments/index.php(22): do_post_request('https://api.sta...', '')
  #1 {main}
    thrown in /var/www/secomments/index.php on line 14
  </code></pre>
  
  <p>Does anyone have any ideas as to what might be causing this, and what one would do to fix it?</p>