方法一：

$arr = array(1, 2, 3, 4, 5, 6, 7, 8);
$length = count($arr);
echo "数组中元素的个数为：" . $length;

方法二：

$arr = array(1, 2, 3, 4, 5, 6, 7, 8);
$count = 0;
foreach ($arr as $element) {
  $count++;
}
echo "数组中元素的个数为：" . $count;