mirror of
https://github.com/sigmasternchen/php-doc-en
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408baf1537
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@312690 c90b9560-bf6c-de11-be94-00142212c4b1
331 lines
7.7 KiB
XML
331 lines
7.7 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="function.json-decode" xmlns="http://docbook.org/ns/docbook">
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<refnamediv>
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<refname>json_decode</refname>
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<refpurpose>Decodes a JSON string</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>mixed</type><methodname>json_decode</methodname>
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<methodparam><type>string</type><parameter>json</parameter></methodparam>
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<methodparam choice="opt"><type>bool</type><parameter>assoc</parameter><initializer>false</initializer></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>depth</parameter><initializer>512</initializer></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>options</parameter><initializer>0</initializer></methodparam>
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</methodsynopsis>
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<para>
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Takes a JSON encoded string and converts it into a PHP variable.
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>json</parameter></term>
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<listitem>
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<para>
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The <parameter>json</parameter> <type>string</type> being decoded.
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</para>
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<para>
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This function only works with UTF-8 encoded data.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>assoc</parameter></term>
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<listitem>
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<para>
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When &true;, returned <type>object</type>s will be converted into
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associative <type>array</type>s.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>depth</parameter></term>
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<listitem>
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<para>
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User specified recursion depth.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>options</parameter></term>
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<listitem>
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<para>
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Bitmask of JSON decode options. Currently only
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<constant>JSON_BIGINT_AS_STRING</constant>
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is supported (default is to cast large integers as floats)
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Returns the value encoded in <parameter>json</parameter> in appropriate
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PHP type. Values <literal>true</literal>, <literal>false</literal> and
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<literal>null</literal> (case-insensitive) are returned as &true;, &false;
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and &null; respectively. &null; is returned if the
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<parameter>json</parameter> cannot be decoded or if the encoded
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data is deeper than the recursion limit.
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title><function>json_decode</function> examples</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$json = '{"a":1,"b":2,"c":3,"d":4,"e":5}';
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var_dump(json_decode($json));
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var_dump(json_decode($json, true));
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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object(stdClass)#1 (5) {
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["a"] => int(1)
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["b"] => int(2)
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["c"] => int(3)
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["d"] => int(4)
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["e"] => int(5)
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}
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array(5) {
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["a"] => int(1)
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["b"] => int(2)
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["c"] => int(3)
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["d"] => int(4)
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["e"] => int(5)
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}
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]]>
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</screen>
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</example>
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<example>
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<title>Accessing invalid object properties</title>
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<simpara>
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Accessing elements within an object that contain characters not
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permitted under PHP's naming convention (e.g. the hyphen) can be
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accomplished by encapsulating the element name within braces and the apostrophe.
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</simpara>
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<programlisting role="php">
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<![CDATA[
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<?php
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$json = '{"foo-bar": 12345}';
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$obj = json_decode($json);
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print $obj->{'foo-bar'}; // 12345
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?>
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]]>
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</programlisting>
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</example>
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<example>
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<title>common mistakes using <function>json_decode</function></title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// the following strings are valid JavaScript but not valid JSON
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// the name and value must be enclosed in double quotes
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// single quotes are not valid
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$bad_json = "{ 'bar': 'baz' }";
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json_decode($bad_json); // null
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// the name must be enclosed in double quotes
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$bad_json = '{ bar: "baz" }';
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json_decode($bad_json); // null
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// trailing commas are not allowed
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$bad_json = '{ bar: "baz", }';
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json_decode($bad_json); // null
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?>
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]]>
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</programlisting>
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</example>
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<example>
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<title><parameter>depth</parameter> errors</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// Encode the data.
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$json = json_encode(
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array(
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1 => array(
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'English' => array(
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'One',
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'January'
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),
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'French' => array(
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'Une',
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'Janvier'
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)
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)
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)
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);
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// Define the errors.
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$constants = get_defined_constants(true);
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$json_errors = array();
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foreach ($constants["json"] as $name => $value) {
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if (!strncmp($name, "JSON_ERROR_", 11)) {
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$json_errors[$value] = $name;
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}
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}
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// Show the errors for different depths.
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foreach (range(4, 3, -1) as $depth) {
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var_dump(json_decode($json, true, $depth));
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echo 'Last error: ', $json_errors[json_last_error()], PHP_EOL, PHP_EOL;
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}
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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array(1) {
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[1]=>
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array(2) {
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["English"]=>
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array(2) {
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[0]=>
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string(3) "One"
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[1]=>
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string(7) "January"
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}
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["French"]=>
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array(2) {
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[0]=>
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string(3) "Une"
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[1]=>
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string(7) "Janvier"
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}
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}
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}
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Last error: JSON_ERROR_NONE
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NULL
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Last error: JSON_ERROR_DEPTH
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]]>
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</screen>
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</example>
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<example>
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<title><function>json_decode</function> of large integers</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$json = '12345678901234567890';
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var_dump(json_decode($json));
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var_dump(json_decode($json, false, 512, JSON_BIGINT_AS_STRING));
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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float(1.2345678901235E+19)
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string(20) "12345678901234567890"
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]]>
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</screen>
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</example>
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</para>
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</refsect1>
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<refsect1 role="notes">
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&reftitle.notes;
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<note>
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<para>
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The JSON spec is not JavaScript, but a subset of JavaScript.
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</para>
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</note>
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<note>
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<para>
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In the event of a failure to decode, <function>json_last_error</function>
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can be used to determine the exact nature of the error.
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</para>
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</note>
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</refsect1>
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<refsect1 role="changelog">
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&reftitle.changelog;
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<para>
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<informaltable>
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<tgroup cols="2">
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<thead>
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<row>
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<entry>&Version;</entry>
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<entry>&Description;</entry>
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</row>
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</thead>
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<tbody>
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<row>
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<entry>5.4.0</entry>
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<entry>
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The <parameter>options</parameter> parameter was added.
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</entry>
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</row>
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<row>
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<entry>5.3.0</entry>
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<entry>Added the optional <parameter>depth</parameter>. The default recursion depth was increased from 128 to 512</entry>
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</row>
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<row>
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<entry>5.2.3</entry>
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<entry>The nesting limit was increased from 20 to 128</entry>
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</row>
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</tbody>
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</tgroup>
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</informaltable>
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</para>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><function>json_encode</function></member>
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<member><function>json_last_error</function></member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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