PHP输出JSON格式数据方式（简单php输出json数据）满满干货

<?php
$libstatis='{
“code”: 0,
“data”: [{
“answer_count”: 14,
“created_at”: “2019-09-06 16:35:06”,
“id”: 1,
“level”: 1,
“name”: “初级题库”,
“questions_count”: 171
}, {
“answer_count”: 9,
“created_at”: “2019-09-06 16:35:20”,
“id”: 2,
“level”: 2,
“name”: “中级题库”,
“questions_count”: 15
}, {
“answer_count”: 0,
“created_at”: “2019-09-06 16:35:30”,
“id”: 3,
“level”: 3,
“name”: “高级题库”,
“questions_count”: 0
}],
“message”: “操作成功”
}’;

echo $libstatis;