PHP中如何使用count()函数

count  ( mixed $arr , [int $mode])

<?php
$a[0] = 1;
$a[1] = 3;
$a[2] = 5;
var_dump(count($a));
?>

<?php
    $arr2 = array(&#39;apple&#39;, &#39;banana&#39;, array(&#39;cat&#39;, &#39;camel&#39;), &#39;dog&#39;);
    $count1 = count($arr2); // 4
    $count2 = count($arr2, 1); // 6
?>

<?php
class People {
  private $name;
  private $sex;
  private $age;
}
 
echo count(new People()); // 1
echo "<br>";
$p1=new People();
$c2 = count((array) $p1); 
echo $c2;// 3
?>