blocks|key|3130|text|mb_detect_encoding的返回可能不正确：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3131|$data+=+iconv('UTF-8',+'ISO-8859-1',+'La+Tronche+Hôpital');
var_dump(
++++mb_detect_encoding($data),
++++mb_detect_encoding($data,+array('ISO-8859-1',+'UTF-8'))
);|code-block|syntax|javascript|3132|根据默认的检测顺序，上面可能会返回不同的结果，因此编码被错误地报告为UTF-8。(Here's+a+larger+example.)|3133|您的数据很可能没有编码为UTF-8，因此json_encode返回false。在JSON编码之前，您应该考虑将字符串转换为UTF-8：|3134|$fromEncoding+=+'ISO-8859-1';+//+This+depends+on+the+data

array_walk_recursive($array,+function+(&$value,+$key,+$fromEncoding)+{
++++if+(is_string($value))+{
++++++++$value+=+iconv($fromEncoding,+'UTF-8',+$value);
++++}
},+$fromEncoding);|3135|entityMap|0|LINK|mutability|MUTABLE|url|http://3v4l.org/i7WEC^0|0|I|0|0|15|N|0|0|K|B|X|5|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|D|@$9|13|A|14|1|15]]|E|$]]|$1|M|3|N|5|6|7|16|8|@$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|1B|8|@]|D|@]|E|$I|J]]|$1|Q|3|-4|5|6|7|1C|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

The return of <code>mb_detect_encoding</code> may not be correct:

<pre><code>$data = iconv('UTF-8', 'ISO-8859-1', 'La Tronche Hôpital');
var_dump(
 mb_detect_encoding($data),
 mb_detect_encoding($data, array('ISO-8859-1', 'UTF-8'))
);
</code></pre>

Depending on the default detection order, the above may return different results, so the encoding is falsely being reported as UTF-8. (<a href="http://3v4l.org/i7WEC" rel="nofollow">Here's a larger example</a>.)

It is likely that your data is not encoded as UTF-8, so <code>json_encode</code> is returning <code>false</code>. You should look at converting your strings to UTF-8 before JSON-encoding:

<pre><code>$fromEncoding = 'ISO-8859-1'; // This depends on the data

array_walk_recursive($array, function (&amp;$value, $key, $fromEncoding) {
 if (is_string($value)) {
 $value = iconv($fromEncoding, 'UTF-8', $value);
 }
}, $fromEncoding);
</code></pre>

blocks|key|3161|text|Matthieu+Riegler提出了非常好的解决方案，但是我不得不稍微修改它来处理对象：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3162|function+utf8ize($d)+{
++++if+(is_array($d))+
++++++++foreach+($d+as+$k+=>+$v)+
++++++++++++$d[$k]+=+utf8ize($v);

+++++else+if(is_object($d))
++++++++foreach+($d+as+$k+=>+$v)+
++++++++++++$d->$k+=+utf8ize($v);

+++++else+
++++++++return+utf8_encode($d);

++++return+$d;
}|code-block|syntax|javascript|3163|另请注意：json_last_error()在调试json_encode()/json_encode()函数时可能很有帮助。|offset|length|3164|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/function.json-last-error.php^0|0|0|5|H|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@$I|V|J|W|1|X]]|A|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

Matthieu Riegler presented really good solution however I had to slightly modify it to handle objects too: 

<pre><code>function utf8ize($d) {
 if (is_array($d)) 
 foreach ($d as $k =&gt; $v) 
 $d[$k] = utf8ize($v);

 else if(is_object($d))
 foreach ($d as $k =&gt; $v) 
 $d-&gt;$k = utf8ize($v);

 else 
 return utf8_encode($d);

 return $d;
}
</code></pre>

One more note: <a href="http://php.net/manual/en/function.json-last-error.php" rel="noreferrer" title="json_last_error&#40;&#41;">json_last_error()</a> may be helpful in debugging json_encode()/json_encode() functions.

blocks|key|3189|text|Adam+Bubela也提出了非常好的解决方案，他帮助我解决了我的问题，下面是简化的函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3190|function+utf8ize($d)
{+
++++if+(is_array($d)+%7C%7C+is_object($d))
++++++++foreach+($d+as+&$v)+$v+=+utf8ize($v);
++++else
++++++++return+utf8_encode($d);

++++return+$d;
}|code-block|syntax|javascript|3191|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Adam Bubela also presented really good solution who helped me solved my problem, and here is the simplified function :

<pre><code>function utf8ize($d)
{ 
 if (is_array($d) || is_object($d))
 foreach ($d as &amp;$v) $v = utf8ize($v);
 else
 return utf8_encode($d);

 return $d;
}
</code></pre>

blocks|key|220032|text|这个公认的答案是有效的。但是，如果您从MySQL获取数据(就像我一样)，那么有一种更简单的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|220033|打开数据库后，在查询之前可以使用mysqli设置字符集，如下所示：|220034|/*+change+character+set+to+utf8+%7C+Procedural*/
if+(!mysqli_set_charset($link,+"utf8"))+{
++++printf("Error+loading+character+set+utf8:+%25s\n",+mysqli_error($link));
++++exit();
}|code-block|syntax|javascript|220035|或|220036|/*+change+character+set+to+utf8+%7C+Object+Oriented*/
if+(!$mysqli->set_charset("utf8"))+{
++++++++printf("Error+loading+character+set+utf8:+%25s\n",+$mysqli->error);
++++++++exit();
+}|220037|链接：http://php.net/manual/en/mysqli.set-charset.php|offset|length|220038|entityMap|0|LINK|mutability|MUTABLE|url|http://php.net/manual/en/mysqli.set-charset.php^0|0|0|0|0|0|3|1B|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|10|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|11|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|13|8|@]|9|@$O|14|P|15|1|16]]|A|$]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

This accepted answer works. But in case you are getting your data from MySQL (as I was) there is an easier way.

Once you open you database, before you query you can set the character set using mysqli as follows:

<pre><code>/* change character set to utf8 | Procedural*/
if (!mysqli_set_charset($link, "utf8")) {
 printf("Error loading character set utf8: %s\n", mysqli_error($link));
 exit();
}
</code></pre>

OR

<pre><code>/* change character set to utf8 | Object Oriented*/
if (!$mysqli-&gt;set_charset("utf8")) {
 printf("Error loading character set utf8: %s\n", $mysqli-&gt;error);
 exit();
 }
</code></pre>

LINK: 
<a href="http://php.net/manual/en/mysqli.set-charset.php" rel="noreferrer">http://php.net/manual/en/mysqli.set-charset.php</a>

blocks|key|3232|text|对我来说，这个问题的答案是在我的PDO连接中设置charset=utf8。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3233|$dbo+=+new+PDO('mysql:host=localhost;dbname=yourdb;charset=utf8',+$username,+$password);|code-block|syntax|javascript|3234|entityMap^0|O|C|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

For me, the answer to this problem was setting <code>charset=utf8</code> in my PDO connection.

<pre><code>$dbo = new PDO('mysql:host=localhost;dbname=yourdb;charset=utf8', $username, $password);
</code></pre>

blocks|key|3275|text|我在运行旧版本PHP+(5.2)的服务器上遇到了这个问题。我使用的是JSON_FORCE_OBJECT标志，显然在5.3之前还不支持|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3276|所以，如果你正在使用这个标志，一定要检查你的版本！|3277|一种解决方法似乎只是在编码之前强制转换为对象，例如：|3278|json_encode((object)$myvar);|code-block|syntax|javascript|3279|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I ran into this issue on a server running an older version of PHP (5.2). I was using the JSON_FORCE_OBJECT flag, and apparently that isn't supported until 5.3

So if you're using that flag be sure to check your version!

A workaround appears to be just casting to an object before encoding, like:

<pre><code>json_encode((object)$myvar);
</code></pre>

blocks|key|3335|text|我改进了Adam+Bubela的答案。我只是讨厌区块没有被{和}关闭。它更干净，而且不会引入错误，或者可能是因为我过去确实使用过Perl+:)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3336|<?php

class+App_Updater_String_Util+{++++
++++/**
+++++*+Usage:+App_Updater_String_Util::utf8_encode(+$data+);
+++++*
+++++*+@param+mixed+$d
+++++*+@return+mixed
+++++*+@see+http://stackoverflow.com/questions/19361282/why-would-json-encode-returns-an-empty-string
+++++*/
++++public+static+function+utf8_encode($d)+{
++++++++if+(is_array($d))+{
++++++++++++foreach+($d+as+$k+=>+$v)+{
++++++++++++++++$d[$k]+=+self::utf8_encode($v);
++++++++++++}
++++++++}+elseif+(is_object($d))+{
++++++++++++foreach+($d+as+$k+=>+$v)+{
++++++++++++++++$d->$k+=+self::utf8_encode($v);
++++++++++++}
++++++++}+elseif+(is_scalar($d))+{
++++++++++++$d+=+utf8_encode($d);
++++++++}

++++++++return+$d;
++++}
}

?>|code-block|syntax|javascript|3337|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I have improved Adam Bubela's answer.
I just hate it when blocks are not closed by { and }.
It's cleaner and you don't introduce bugs or maybe it's that I did use Perl in the past :)

<pre><code>&lt;?php

class App_Updater_String_Util { 
 /**
 * Usage: App_Updater_String_Util::utf8_encode( $data );
 *
 * @param mixed $d
 * @return mixed
 * @see http://stackoverflow.com/questions/19361282/why-would-json-encode-returns-an-empty-string
 */
 public static function utf8_encode($d) {
 if (is_array($d)) {
 foreach ($d as $k =&gt; $v) {
 $d[$k] = self::utf8_encode($v);
 }
 } elseif (is_object($d)) {
 foreach ($d as $k =&gt; $v) {
 $d-&gt;$k = self::utf8_encode($v);
 }
 } elseif (is_scalar($d)) {
 $d = utf8_encode($d);
 }

 return $d;
 }
}

?&gt;
</code></pre>

blocks|key|220149|text|对这些字符串使用utf8_encode()解决了我的问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|220150|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

using utf8_encode() on those string solved my problem.

blocks|key|220182|text|我从ob_get_clean()获取数据，也遇到了同样的问题，但上面的解决方案对我不起作用。在我的案例中，解决方案是这样的，也许它会对某人有所帮助。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|220183|$var+=+mb_convert_encoding($var,+'UTF-8');|code-block|syntax|javascript|220184|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I was getting data from ob_get_clean() and had the same problem, but above solutions don't work for me. In my case solution was this, maybe it will help somebody.

<pre><code>$var = mb_convert_encoding($var, 'UTF-8');
</code></pre>

blocks|key|220248|text|如果从数据库中获取此数据，请在从数据库中获取参数时在连接中使用mysqli_set_charset($connection,+"utf8");|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|220249|entityMap^0|V|14|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

If you get this data from a database, use <code>mysqli_set_charset($connection, "utf8");</code> in connection when get the params from database

blocks|key|3487|text|这个问题有时会出现--你没有传递报头访问控制。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3488|在我的例子中，如果我在json_encode之前添加了任何回显。正在显示结果，否则会出现空白页面。|3489|我添加了|3490|header('Access-Control-Allow-Origin:+*');+|code-block|syntax|javascript|3491|我的问题就解决了。|3492|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|R|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

this problem comes sometimes - you are not passing header access control.

In my case if I was added any echo before json_encode. It was showing result otherwise blank page was coming. 

I added 

<pre><code>header('Access-Control-Allow-Origin: *'); 
</code></pre>

and my problem resolved.

blocks|key|3563|text|由于输出无论如何都会以JSON+(字符串)结束，下面是一个可以处理所有类型的变量的函数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3564|++++function+utf8ize($arg)
++++{
++++++++if+(is_array($arg))
++++++++++++foreach+($arg+as+$k+=>+$v)
++++++++++++++++$arg[$k]+=+utf8ize($v);
+++++++++else+if(is_object($arg))
++++++++++++return+utf8ize((array)+$arg);
+++++++++else
++++++++++++return+utf8_encode(strval($arg));
++++++++return+$arg;
++++}|code-block|syntax|javascript|3565|这个答案是Matthieu+Riegler和Adam+Bubela的答案的改进，但这个答案可以处理所有类型的变量/数据类型(例如:资源，如文件句柄/流/phpgd/sql连接)|3566|当参数为object时，我使用强制转换为数组，以防止在object属性为read+only或private/protected时出错。|3567|此外，在else情况下，我使用strval来处理其他数据类型，如resource|offset|length|style|CODE|3568|我使用这个函数将一个变量‘强制’成字符串(例如:当var_dump-ing或登录到文本文件时)|3569|entityMap^0|0|0|0|0|4|4|F|6|W|8|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|Y|8|@$M|Z|N|10|O|P]|$M|11|N|12|O|P]|$M|13|N|14|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|15|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|16|8|@]|9|@]|A|$]]]|T|$]]

Since the output is going to end up as JSON (string) anyway, here is a function that can handle all kind of variable type:
<pre class="lang-php prettyprint-override"><code> function utf8ize($arg)
 {
 if (is_array($arg))
 foreach ($arg as $k =&gt; $v)
 $arg[$k] = utf8ize($v);
 else if(is_object($arg))
 return utf8ize((array) $arg);
 else
 return utf8_encode(strval($arg));
 return $arg;
 }
</code></pre>
This answer is improvement from Matthieu Riegler and Adam Bubela's answer, but this one can handle all type of variable / data type (e.g.: resource like file handle/stream/phpgd/sql connection)
I'm using cast as array when the argument is object in order to prevent error if the object property is read only or private/protected.
Also, on <code>else</code> case, I <code>strval</code> it to handle other data type like <code>resource</code>
I'm using this function to 'force' a variable into string (e.g.: when var_dump-ing or logging to text file)

I have a simple php structure with 3 nested arrays. 

I do not use particular objects and I build myself the arrays with 2 nested loops. 

Here is a sample of the var_dump of the array I want to convert to Json. 

<pre><code>array (size=2)
 'tram B' =&gt; 
 array (size=2)
 0 =&gt; 
 array (size=3)
 'name' =&gt; string 'Ile Verte' (length=9)
 'distance' =&gt; int 298
 'stationID' =&gt; int 762
 1 =&gt; 
 array (size=3)
 'name' =&gt; string 'La Tronche Hôpital' (length=18)
 'distance' =&gt; int 425
 'stationID' =&gt; int 771
 16 =&gt; 
 array (size=4)
 0 =&gt; 
 array (size=3)
 'name' =&gt; string 'Bastille' (length=8)
 'distance' =&gt; int 531
 'stationID' =&gt; int 397
 1 =&gt; 
 array (size=3)
 'name' =&gt; string 'Xavier Jouvin' (length=13)
 'distance' =&gt; int 589
 'stationID' =&gt; int 438
</code></pre>

In another script I have a similar structure and <code>json_encode</code> works fine. 
So I don't understand why <code>json_encode</code> won't work here.

Edit : there seems to be a problem with the encoding. When <code>mb_detect_encoding</code> returns ASCII, the <code>json_encode</code> works but when it returns UTF8, it doesn't work anymore. 

Edit2 : <code>json_last_error()</code> returns <code>JSON_ERROR_UTF8</code> which means : <a href="http://fr2.php.net/manual/en/function.json-last-error.php" rel="noreferrer">Malformed UTF-8 characters, possibly incorrectly encoded</a>.

Why would json_encode return an empty string

数据库

服务器

MySQL

JSON

Perl

我有一个简单的php结构，有3个嵌套数组。我不使用特定的对象，我自己构建带有2个嵌套循环的数组。下面是我想要转换为Json的数组的var_dump示例。array (size=2)  'tram B' =>     array (size=2)      0 =>         array (size=3)     ...

问为什么json_encode会返回空字符串
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