php-doc-en/reference/json/functions/json-encode.xml

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<refentry xml:id="function.json-encode" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>json_encode</refname>
  <refpurpose>Returns the JSON representation of a value</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>string</type><methodname>json_encode</methodname>
   <methodparam><type>mixed</type><parameter>value</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>options</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>
  <para>
   Returns a string containing the JSON representation of 
   <parameter>value</parameter>.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>value</parameter></term>
     <listitem>
      <para>
       The <parameter>value</parameter> being encoded. Can be any type except
       a <type>resource</type>.
      </para>
      <para>
       This function only works with UTF-8 encoded data.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>options</parameter></term>
     <listitem>
      <para>
       Bitmask consisting of <constant>JSON_HEX_QUOT</constant>,
       <constant>JSON_HEX_TAG</constant>,
       <constant>JSON_HEX_AMP</constant>,
       <constant>JSON_HEX_APOS</constant>,
       <constant>JSON_FORCE_OBJECT</constant>.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns a JSON encoded <type>string</type> on success.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>5.3.0</entry>
       <entry>
        The <parameter>options</parameter> parameter was added.
       </entry>
      </row>
      <row>
       <entry>5.2.1</entry>
       <entry>
        Added support for JSON encoding of basic types.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title>A <function>json_encode</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$arr = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);

echo json_encode($arr);
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
{"a":1,"b":2,"c":3,"d":4,"e":5}
]]>
    </screen>
   </example>

   <example>
    <title>A <function>json_encode</function> example showing all the options in action</title>
    <programlisting role="php">
<![CDATA[
<?php
$a = array('<foo>',"'bar'",'"baz"','&blong&');

echo "Normal: ", json_encode($a), "\n";
echo "Tags: ",   json_encode($a,JSON_HEX_TAG), "\n";
echo "Apos: ",   json_encode($a,JSON_HEX_APOS), "\n";
echo "Quot: ",   json_encode($a,JSON_HEX_QUOT), "\n";
echo "Amp: ",    json_encode($a,JSON_HEX_AMP), "\n";
echo "All: ",    json_encode($a,JSON_HEX_TAG|JSON_HEX_APOS|JSON_HEX_QUOT|JSON_HEX_AMP), "\n\n";

$b = array();

echo "Empty array output as array: ", json_encode($b), "\n";
echo "Empty array output as object: ", json_encode($b, JSON_FORCE_OBJECT), "\n\n";

$c = array(array(1,2,3));

echo "Non-associative array output as array: ", json_encode($c), "\n";
echo "Non-associative array output as object: ", json_encode($c, JSON_FORCE_OBJECT), "\n\n";

$d = array('foo' => 'bar', 'baz' => 'long');

echo "Associative array always output as object: ", json_encode($d), "\n";
echo "Associative array always output as object: ", json_encode($d, JSON_FORCE_OBJECT), "\n\n";
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
Normal: ["<foo>","'bar'","\"baz\"","&blong&"]
Tags: ["\u003Cfoo\u003E","'bar'","\"baz\"","&blong&"]
Apos: ["<foo>","\u0027bar\u0027","\"baz\"","&blong&"]
Quot: ["<foo>","'bar'","\u0022baz\u0022","&blong&"]
Amp: ["<foo>","'bar'","\"baz\"","\u0026blong\u0026"]
All: ["\u003Cfoo\u003E","\u0027bar\u0027","\u0022baz\u0022","\u0026blong\u0026"]

Empty array output as array: []
Empty array output as object: {}

Non-associative array output as array: [[1,2,3]]
Non-associative array output as object: {"0":{"0":1,"1":2,"2":3}}

Associative array always output as object: {"foo":"bar","baz":"long"}
Associative array always output as object: {"foo":"bar","baz":"long"}
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    In the event of a failure to encode, <function>json_last_error</function>
    can be used to determine the exact nature of the error.
   </para>
  </note>
 </refsect1>

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

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