function httpPost($url,$params)
{
  $postData = '';
   //create name value pairs seperated by &
   foreach($params as $k => $v)
   {
      $postData .= $k . '='.$v.'&';
   }
   rtrim($postData, '&');

    $ch = curl_init();

    curl_setopt($ch,CURLOPT_URL,$url);
    curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);
    curl_setopt($ch,CURLOPT_HEADER, false);
    curl_setopt($ch, CURLOPT_POST, count($postData));
    curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);

    $output=curl_exec($ch);

    curl_close($ch);
    return $output;

}


$params = array(

    'action' => 'UserCreate',

    'cityCombo' => '1'

);

httpPost("http://www.site.com/reg.php",$params);

}