php动态绑定变量的用法

private function bindVars($stmt,$params) {
  if ($params != null) {
    $types = ''; //initial sting with types
    foreach($params as $param) {
 //for each element, determine type and add
      if(is_int($param)) {
        $types .= 'i'; //integer
      } elseif (is_float($param)) {
        $types .= 'd'; //double
      } elseif (is_string($param)) {
        $types .= 's'; //string
      } else {
        $types .= 'b';
 //blob and unknown
      }
    }
    $bind_names[] = $types;
 //first param needed is the type string
 // eg: 'issss'
    for ($i=0; $i<count($params);$i++) {
 //go through incoming params and added em to array
      $bind_name = 'bind' . $i;
   //give them an arbitrary name
      $$bind_name = $params[$i];
   //add the parameter to the variable variable
      $bind_names[] = &$$bind_name;
   //now associate the variable as an element in an array
    }
    //call the function bind_param with dynamic params
    call_user_func_array(array($stmt,'bind_param'),$bind_names);
  }
  return $stmt; //return the bound statement