How to implement json encoding conversion in php

<?php
/*
 * json
 */
$books = array(&#39;key1&#39;=>&#39;value1&#39;,&#39;key2&#39;=>&#39;value2&#39;,&#39;key3&#39;=>array(&#39;key4&#39;=>&#39;value4&#39;,&#39;key5&#39;=>&#39;value5&#39;));
$json = json_encode($books);
$rejson = json_decode($json,true);
echo &#39;原数组：<br/>&#39;;
print_r($books);
echo &#39;<br/><br/>&#39;;
echo &#39;经json编码后：<br/>&#39;;
print $json."<br/>";
echo &#39;<br/>&#39;;
echo &#39;经json解码后：<br/>&#39;;
print_r($rejson);
echo &#39;<br/><br/>&#39;;
//实例
$jsonn = &#39;{"error_code":"400","request":"\/Router\/aQConnectError","api_code":40006,"error":"\u4f20\u5165\u7684\u63a5\u53e3\u53c2\u6570\u51fa\u9519\uff0c\u53c2\u6570openid\u672a\u8bbe\u5b9a\u3002"}&#39;;
print_r(json_decode($jsonn));
?>