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Luffy
351 lines
9.1 KiB
XML
351 lines
9.1 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<!-- EN-Revision: 9f2e30a00afda6d6b6a3e19b13956150c2eaf2c1 Maintainer: jhdxr Status: ready -->
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<!-- CREDITS: Luffy, mowangjuanzi -->
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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>对 JSON 格式的字符串进行解码</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 class="union"><type>bool</type><type>null</type></type><parameter>associative</parameter><initializer>&null;</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>flags</parameter><initializer>0</initializer></methodparam>
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</methodsynopsis>
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<para>
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接受一个 JSON 编码的字符串并且把它转换为 PHP 值。
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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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待解码的 <parameter>json</parameter> <type>string</type> 格式的字符串。
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</para>
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<para>
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这个函数仅能处理 UTF-8 编码的数据。
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</para>
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&json.implementation.superset;
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>associative</parameter></term>
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<listitem>
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<para>
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当为 &true; 时，JSON 对象将返回关联 &array;；当为 &false; 时，JSON 对象将返回
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&object;。当为 &null; 时，JSON 对象将返回关联 &array; 或 &object;，这取决于是否在
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<parameter>flags</parameter> 中设置 <constant>JSON_OBJECT_AS_ARRAY</constant>。
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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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需要解码的结构，其最大嵌套深度。该值必须大于 <literal>0</literal> 或者小于等于 <literal>2147483647</literal>。
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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>flags</parameter></term>
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<listitem>
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<para>
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由 <constant>JSON_BIGINT_AS_STRING</constant>、<constant>JSON_INVALID_UTF8_IGNORE</constant>、<constant>JSON_INVALID_UTF8_SUBSTITUTE</constant>、<constant>JSON_OBJECT_AS_ARRAY</constant>、<constant>JSON_THROW_ON_ERROR</constant>
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组成的掩码。这些常量的行为在 <link linkend="json.constants">JSON constants</link> 页面有进一步描述。
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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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返回在 <parameter>json</parameter> 中编码的数据作为合适的 PHP 类型。没有引号的值
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<literal>true</literal>、<literal>false</literal> 和 <literal>null</literal>
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会相应地返回 &true;、&false; 和 &null;。如果 <parameter>json</parameter>
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无法被解码，或者编码数据深度超过了嵌套限制的话，将会返回 &null;。
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</para>
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</refsect1>
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<refsect1 role="errors">
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&reftitle.errors;
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<para>
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如果 <parameter>depth</parameter> 超出允许的范围，自 PHP 8.0.0 起将会抛出
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<classname>ValueError</classname>，在此之前的版本将会引发
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<constant>E_WARNING</constant> 级别的错误。
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</para>
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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>7.3.0</entry>
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<entry>
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<parameter>flags</parameter> 新增 <constant>JSON_THROW_ON_ERROR</constant>。
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</entry>
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</row>
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<row>
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<entry>7.2.0</entry>
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<entry>
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现在 <parameter>associative</parameter> 允许为 null。
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</entry>
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</row>
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<row>
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<entry>7.2.0</entry>
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<entry>
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<parameter>flags</parameter> 新增 <constant>JSON_INVALID_UTF8_IGNORE</constant>、<constant>JSON_INVALID_UTF8_SUBSTITUTE</constant>。
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</entry>
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</row>
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<row>
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<entry>7.1.0</entry>
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<entry>
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An empty JSON key ("") can be encoded to the empty object property
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instead of using a key with value <literal>_empty_</literal>.
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</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="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> 的例子</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($bad_json); // null
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?>
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]]>
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</programlisting>
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</example>
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<example>
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<title><parameter>depth</parameter> errors</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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// Encode some data with a maximum depth of 4 (array -> array -> array -> string)
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$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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// Show the errors for different depths.
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var_dump(json_decode($json, true, 4));
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echo 'Last error: ', json_last_error_msg(), PHP_EOL, PHP_EOL;
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var_dump(json_decode($json, true, 3));
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echo 'Last error: ', json_last_error_msg(), PHP_EOL, PHP_EOL;
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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: No error
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NULL
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Last error: Maximum stack depth exceeded
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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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$json = '{"number": 12345678901234567890}';
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var_dump(json_decode($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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object(stdClass)#1 (1) {
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["number"]=>
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float(1.2345678901235E+19)
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}
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object(stdClass)#1 (1) {
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["number"]=>
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string(20) "12345678901234567890"
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}
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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="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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<member><function>json_last_error_msg</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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