PHP json_encode 函数返回空白 {}

Question

我正在尝试使用 AJAX 调用来获取一些数据并通过 JSON 将多条数据返回给调用者。它适用于某些包含简单输出的测试。但是，当返回的元素之一是 HTML 时，它就不起作用。对此有什么想法吗？

// get_answer() pulls some HTML back from an XML document
$answer = $_SESSION['quiz_session']->get_answer();

// test output to make sure everything is working
echo $answer;

/** sample output **
 *     
      <div>
        <p>
            <b>
                <span class="gloss-def">a downward slope</span>
            </b>
        </p>
        <p>Because the village was situated on the 
            <i>declivity</i> of a hill, it never flooded.
        </p>
        <p>
            <i>Synonyms: decline; descent; grade; slant; tilt</i>
        </p>
      </div>
 *
 ** end sample output **/

 echo json_encode($answer);
 // will output {}

Answer 1

尝试将 $answer 添加到 stdClass 或数组，例如

echo json_encode(array("answer"=>$answer));