archived-doc-zh/reference/json/functions/json-last-error.xml

<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.json-last-error" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>json_last_error</refname>
  <refpurpose>返回最后发生的错误</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>int</type><methodname>json_last_error</methodname>
   <void />
  </methodsynopsis>
  <para>
   没有指定 <constant>JSON_THROW_ON_ERROR</constant>时，返回上一次 JSON 验证/编码/解码时发生的最后一个错误（如果有）。
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  &no.function.parameters;
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   返回一个整型（integer），这个值会是以下的常量之一：
  </para>
  <table>
   <title>JSON 错误码</title>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>常量</entry>
      <entry>含义</entry>
      <entry>可用性</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry><constant>JSON_ERROR_NONE</constant></entry>
      <entry>没有错误发生</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_DEPTH</constant></entry>
      <entry>到达了最大堆栈深度</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_STATE_MISMATCH</constant></entry>
      <entry>无效或异常的 JSON</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_CTRL_CHAR</constant></entry>
      <entry>控制字符错误，可能是编码不对</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_SYNTAX</constant></entry>
      <entry>语法错误</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_UTF8</constant></entry>
      <entry>异常的 UTF-8 字符，也许是因为不正确的编码。</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_RECURSION</constant></entry>
      <entry>One or more recursive references in the value to be encoded</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_INF_OR_NAN</constant></entry>
      <entry>
       One or more
       <link linkend="language.types.float.nan"><constant>NAN</constant></link>
       or <link linkend="function.is-infinite"><constant>INF</constant></link>
       values in the value to be encoded
      </entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_UNSUPPORTED_TYPE</constant></entry>
      <entry>指定的类型，值无法编码。</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_INVALID_PROPERTY_NAME</constant></entry>
      <entry>指定的属性名无法编码。</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_UTF16</constant></entry>
      <entry>畸形的 UTF-16 字符，可能因为字符编码不正确。</entry>
      <entry></entry>
     </row>
    </tbody>
   </tgroup>
  </table>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>json_last_error</function> 例子</title>
    <programlisting role="php">
<![CDATA[
<?php
// 一个有效的 json 字符串
$json[] = '{"Organization": "PHP Documentation Team"}';

// 一个无效的 json 字符串会导致一个语法错误，在这个例子里我们使用 ' 代替了 " 作为引号
$json[] = "{'Organization': 'PHP Documentation Team'}";


foreach ($json as $string) {
    echo 'Decoding: ' . $string;
    json_decode($string);

    switch (json_last_error()) {
        case JSON_ERROR_NONE:
            echo ' - No errors';
        break;
        case JSON_ERROR_DEPTH:
            echo ' - Maximum stack depth exceeded';
        break;
        case JSON_ERROR_STATE_MISMATCH:
            echo ' - Underflow or the modes mismatch';
        break;
        case JSON_ERROR_CTRL_CHAR:
            echo ' - Unexpected control character found';
        break;
        case JSON_ERROR_SYNTAX:
            echo ' - Syntax error, malformed JSON';
        break;
        case JSON_ERROR_UTF8:
            echo ' - Malformed UTF-8 characters, possibly incorrectly encoded';
        break;
        default:
            echo ' - Unknown error';
        break;
    }

    echo PHP_EOL;
}
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Decoding: {"Organization": "PHP Documentation Team"} - No errors
Decoding: {'Organization': 'PHP Documentation Team'} - Syntax error, malformed JSON
]]>
    </screen>
   </example>
  </para>
  <para>
   <example>
    <title><function>json_encode</function> 的 <function>json_last_error</function></title>
    <programlisting role="php">
<![CDATA[
<?php
// 无效的 UTF8 序列
$text = "\xB1\x31";

$json  = json_encode($text);
$error = json_last_error();

var_dump($json, $error === JSON_ERROR_UTF8);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
string(4) "null"
bool(true)
]]>
    </screen>
   </example>
  </para>
  <para>
   <example>
    <title><function>json_last_error</function> 和 <constant>JSON_THROW_ON_ERROR</constant></title>
    <programlisting role="php">
<![CDATA[
<?php
// 导致 JSON_ERROR_UTF8 的无效 UTF8 序列
json_encode("\xB1\x31");

// 以下不会导致 JSON 错误
json_encode('okay', JSON_THROW_ON_ERROR);

// 前者的 json_encode() 不会改变全局错误状态
var_dump(json_last_error() === JSON_ERROR_UTF8);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
bool(true)
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>json_last_error_msg</function></member>
    <member><function>json_decode</function></member>
    <member><function>json_encode</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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