PHP函数__autoload失效原因及解决方法

<?php
header("Content-type:text/html;charset=utf-8");
$num = 10.4567;
$format_num = sprintf("%.2f",$num);
echo $format_num;  //10.46
?>

<?php
header("Content-type:text/html;charset=utf-8");
$num = 10.4567;
$format_num = number_format($num,'1');
echo $format_num."
";
$format_num = number_format($num,'2');
 
echo $format_num."
";
$format_num = number_format($num,'3');
echo $format_num;
?>

/* Person.class.php */
<?php
 class Person {
 var $name, $age;
 function __construct ($name, $age)
 {
 $this->name = $name;
 $this->age = $age;
 }
 }
?>
/* no_autoload.php */
<?php
 require_once (”Person.class.php”);
 $person = new Person(”Altair”, 6);
 var_dump ($person);
?>