json_encode在数组上返回null

Question

我想要json_encode一个php数组，但“选择”部分返回null。

Array ([indexer] => 7 [section] => 1 [question] => What does the last paragraph indicate about an optimistic perspective? [answer] => a [choices] => There has never been a culture or religion that is genuinely optimistic`It is “a riddle of the universe”`No enlightened culture sees the world in a truly optimistic manner`Optimistic perspectives are only held by the weak) 

{"indexer":"7","section":"1","question":"What does the last paragraph indicate about an optimistic perspective?","answer":"a","choices":null} 

有什么想法为什么？

编辑：全码：

$check = mysqli_query($con, "select * from questions where section = '$section' and indexer = '$question'"); 
$result = mysqli_fetch_array($check, MYSQLI_ASSOC); 

print_r($result); 
echo json_encode($result); 

Answer 1

json_encode期望你编码为有效的UTF-8的所有内容。如果内容的任何部分是不妥当的UTF-8，json_encode将失败默默的那部分（B

所有字符串数据必须是UTF-8编码。

我的猜测是， “马克未正确UTF-8编码的（但是从CP1252基于编码起源）。

参见json_last_error从JSON模块检索最后错误代码。