php-doc-en/reference/json/functions/json-last-error.xml

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<refentry xml:id="function.json-last-error" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>json_last_error</refname>
  <refpurpose>Returns the last error occurred</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>int</type><methodname>json_last_error</methodname>
   <void />
  </methodsynopsis>
  <para>
   Returns the last error (if any) occurred during the last JSON encoding/decoding,
   which did not specify <constant>JSON_THROW_ON_ERROR</constant>.
  </para>
 </refsect1>

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

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns an integer, the value can be one of the following 
   constants: 
  </para>
  <table>
   <title>JSON error codes</title>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>Constant</entry>
      <entry>Meaning</entry>
      <entry>Availability</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry><constant>JSON_ERROR_NONE</constant></entry>
      <entry>No error has occurred</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_DEPTH</constant></entry>
      <entry>The maximum stack depth has been exceeded</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_STATE_MISMATCH</constant></entry>
      <entry>Invalid or malformed JSON</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_CTRL_CHAR</constant></entry>
      <entry>Control character error, possibly incorrectly encoded</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_SYNTAX</constant></entry>
      <entry>Syntax error</entry>
      <entry></entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_UTF8</constant></entry>
      <entry>Malformed UTF-8 characters, possibly incorrectly encoded</entry>
      <entry>PHP 5.3.3</entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_RECURSION</constant></entry>
      <entry>One or more recursive references in the value to be encoded</entry>
      <entry>PHP 5.5.0</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>PHP 5.5.0</entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_UNSUPPORTED_TYPE</constant></entry>
      <entry>A value of a type that cannot be encoded was given</entry>
      <entry>PHP 5.5.0</entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_INVALID_PROPERTY_NAME</constant></entry>
      <entry>A property name that cannot be encoded was given</entry>
      <entry>PHP 7.0.0</entry>
     </row>
     <row>
      <entry><constant>JSON_ERROR_UTF16</constant></entry>
      <entry>Malformed UTF-16 characters, possibly incorrectly encoded</entry>
      <entry>PHP 7.0.0</entry>
     </row>
    </tbody>
   </tgroup>
  </table>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>json_last_error</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
// A valid json string
$json[] = '{"Organization": "PHP Documentation Team"}';

// An invalid json string which will cause an syntax 
// error, in this case we used ' instead of " for quotation
$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_last_error</function> with <function>json_encode</function></title>
    <programlisting role="php">
<![CDATA[
<?php
// An invalid UTF8 sequence
$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> and <constant>JSON_THROW_ON_ERROR</constant></title>
    <programlisting role="php">
<![CDATA[
<?php
// An invalid UTF8 sequence which causes JSON_ERROR_UTF8
json_encode("\xB1\x31");

// The following does not cause a JSON error
json_encode('okay', JSON_THROW_ON_ERROR);

// The global error state has not been changed by the former json_encode()
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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