我已经搜索了SO，但是找不到答案。我的PHP脚本正在通过http发布接收一些JSON，如下所示：

{
"task": [
{
  "task_id": "3",
  "task_due": "Oct 26 11:25",
  "task_completed": "FALSE",
  "task_desc": "fff",
  "task_time": "20131026_112531",
  "task_name": "fff"
},
{
  "task_id": "2",
  "task_due": "Oct 26 11:25",
  "task_completed": "FALSE",
  "task_desc": "rff",
  "task_time": "20131026_112522",
  "task_name": "xff"
},
{
  "task_id": "1",
  "task_due": "Oct 26 11:25",
  "task_completed": "FALSE",
  "task_desc": "fggg",
  "task_time": "20131026_112516",
  "task_name": "ff"
  }
 ]}

如您所见，这里有3个项目，但是当我将它变成一个PHP数组对象并计算项目时，我返回1，应该为3，这是我的PHP代码：

$json_tasks = $_POST["json_array"];
$task_array = json_decode($json_tasks,true);
echo count($task_array);

并echo count打印出“ 1”而不是“ 3”。