How to submit checkbox values with PHP post method

Answer 1

$checked = array();

foreach ($_POST as $k => $v) {
$subject = $k;
$pattern = '/^checkbox_(\d+)$/';
  if (preg_match($pattern, $subject, $matches)) 
  {
    $checked[] = $matches[1];
  }
}

asort($checked);

foreach ($checked as $key=>$value)
echo $value .' ';