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346 lines
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346 lines
20 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>对 JSON 格式的字符串进行解码</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.json-decode" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">json_decode</h1>
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<p class="verinfo">(PHP 5 >= 5.2.0, PHP 7, PECL json >= 1.2.0)</p><p class="refpurpose"><span class="refname">json_decode</span> — <span class="dc-title">对 JSON 格式的字符串进行解码</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.json-decode-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>json_decode</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$json</code></span>
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[, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$assoc</code><span class="initializer"> = false</span></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$depth</code><span class="initializer"> = 512</span></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$options</code><span class="initializer"> = 0</span></span>
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]]] ) : <span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span></div>
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<p class="para rdfs-comment">
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接受一个 JSON 编码的字符串并且把它转换为 PHP 变量
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.json-decode-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">json</code></dt>
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<dd>
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<p class="para">
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待解码的 <code class="parameter">json</code> <span class="type"><a href="language.types.string.html" class="type string">string</a></span> 格式的字符串。
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</p>
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<p class="para">
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这个函数仅能处理 UTF-8 编码的数据。
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</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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PHP implements a superset of JSON as specified in the original
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<a href="http://www.faqs.org/rfcs/rfc7159" class="link external">» RFC 7159</a>.
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</p>
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</p></blockquote>
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</dd>
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<dt>
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<code class="parameter">assoc</code></dt>
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<dd>
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<p class="para">
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当该参数为 <strong><code>TRUE</code></strong> 时，将返回 <span class="type"><a href="language.types.array.html" class="type array">array</a></span> 而非 <span class="type"><a href="language.types.object.html" class="type object">object</a></span> 。
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</p>
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</dd>
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<dt>
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<code class="parameter">depth</code></dt>
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<dd>
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<p class="para">
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指定递归深度。
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</p>
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</dd>
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<dt>
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<code class="parameter">options</code></dt>
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<dd>
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<p class="para">
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JSON解码的掩码选项。 现在有两个支持的选项。
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第一个是<strong><code>JSON_BIGINT_AS_STRING</code></strong>，
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用于将大整数转为字符串而非默认的float类型。第二个是
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<strong><code>JSON_OBJECT_AS_ARRAY</code></strong>，
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与将<code class="parameter">assoc</code>设置为 <strong><code>TRUE</code></strong> 有相同的效果。
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</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.json-decode-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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Returns the value encoded in <code class="parameter">json</code> in appropriate
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PHP type. Values <em>true</em>, <em>false</em> and
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<em>null</em> are returned as <strong><code>TRUE</code></strong>, <strong><code>FALSE</code></strong> and <strong><code>NULL</code></strong>
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respectively. <strong><code>NULL</code></strong> is returned if the <code class="parameter">json</code> cannot
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be decoded or if the encoded data is deeper than the recursion limit.
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.json-decode-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-4513">
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<p><strong>Example #1 <span class="function"><strong>json_decode()</strong></span> 的例子</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$json </span><span style="color: #007700">= </span><span style="color: #DD0000">'{"a":1,"b":2,"c":3,"d":4,"e":5}'</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$json</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$json</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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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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</pre></div>
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</div>
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</div>
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<div class="example" id="example-4514">
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<p><strong>Example #2 Accessing invalid object properties</strong></p>
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<div class="example-contents"><p>
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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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</p></div>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /><br />$json </span><span style="color: #007700">= </span><span style="color: #DD0000">'{"foo-bar": 12345}'</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$obj </span><span style="color: #007700">= </span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$json</span><span style="color: #007700">);<br />print </span><span style="color: #0000BB">$obj</span><span style="color: #007700">->{</span><span style="color: #DD0000">'foo-bar'</span><span style="color: #007700">}; </span><span style="color: #FF8000">// 12345<br /><br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-4515">
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<p><strong>Example #3 common mistakes using <span class="function"><strong>json_decode()</strong></span></strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /><br /></span><span style="color: #FF8000">// the following strings are valid JavaScript but not valid JSON<br /><br />// the name and value must be enclosed in double quotes<br />// single quotes are not valid <br /></span><span style="color: #0000BB">$bad_json </span><span style="color: #007700">= </span><span style="color: #DD0000">"{ 'bar': 'baz' }"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$bad_json</span><span style="color: #007700">); </span><span style="color: #FF8000">// null<br /><br />// the name must be enclosed in double quotes<br /></span><span style="color: #0000BB">$bad_json </span><span style="color: #007700">= </span><span style="color: #DD0000">'{ bar: "baz" }'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$bad_json</span><span style="color: #007700">); </span><span style="color: #FF8000">// null<br /><br />// trailing commas are not allowed<br /></span><span style="color: #0000BB">$bad_json </span><span style="color: #007700">= </span><span style="color: #DD0000">'{ bar: "baz", }'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$bad_json</span><span style="color: #007700">); </span><span style="color: #FF8000">// null<br /><br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-4516">
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<p><strong>Example #4 <code class="parameter">depth</code> errors</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// Encode the data.<br /></span><span style="color: #0000BB">$json </span><span style="color: #007700">= </span><span style="color: #0000BB">json_encode</span><span style="color: #007700">(<br /> array(<br /> </span><span style="color: #0000BB">1 </span><span style="color: #007700">=> array(<br /> </span><span style="color: #DD0000">'English' </span><span style="color: #007700">=> array(<br /> </span><span style="color: #DD0000">'One'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'January'<br /> </span><span style="color: #007700">),<br /> </span><span style="color: #DD0000">'French' </span><span style="color: #007700">=> array(<br /> </span><span style="color: #DD0000">'Une'</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">'Janvier'<br /> </span><span style="color: #007700">)<br /> )<br /> )<br />);<br /><br /></span><span style="color: #FF8000">// Define the errors.<br /></span><span style="color: #0000BB">$constants </span><span style="color: #007700">= </span><span style="color: #0000BB">get_defined_constants</span><span style="color: #007700">(</span><span style="color: #0000BB">true</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">$json_errors </span><span style="color: #007700">= array();<br />foreach (</span><span style="color: #0000BB">$constants</span><span style="color: #007700">[</span><span style="color: #DD0000">"json"</span><span style="color: #007700">] as </span><span style="color: #0000BB">$name </span><span style="color: #007700">=> </span><span style="color: #0000BB">$value</span><span style="color: #007700">) {<br /> if (!</span><span style="color: #0000BB">strncmp</span><span style="color: #007700">(</span><span style="color: #0000BB">$name</span><span style="color: #007700">, </span><span style="color: #DD0000">"JSON_ERROR_"</span><span style="color: #007700">, </span><span style="color: #0000BB">11</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$json_errors</span><span style="color: #007700">[</span><span style="color: #0000BB">$value</span><span style="color: #007700">] = </span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br /> }<br />}<br /><br /></span><span style="color: #FF8000">// Show the errors for different depths.<br /></span><span style="color: #007700">foreach (</span><span style="color: #0000BB">range</span><span style="color: #007700">(</span><span style="color: #0000BB">4</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">, -</span><span style="color: #0000BB">1</span><span style="color: #007700">) as </span><span style="color: #0000BB">$depth</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$json</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">, </span><span style="color: #0000BB">$depth</span><span style="color: #007700">));<br /> echo </span><span style="color: #DD0000">'Last error: '</span><span style="color: #007700">, </span><span style="color: #0000BB">$json_errors</span><span style="color: #007700">[</span><span style="color: #0000BB">json_last_error</span><span style="color: #007700">()], </span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">, </span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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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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</pre></div>
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</div>
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</div>
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<div class="example" id="example-4517">
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<p><strong>Example #5 <span class="function"><strong>json_decode()</strong></span> of large integers</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$json </span><span style="color: #007700">= </span><span style="color: #DD0000">'{"number": 12345678901234567890}'</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$json</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">json_decode</span><span style="color: #007700">(</span><span style="color: #0000BB">$json</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">, </span><span style="color: #0000BB">512</span><span style="color: #007700">, </span><span style="color: #0000BB">JSON_BIGINT_AS_STRING</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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<div class="example-contents"><p>以上例程会输出：</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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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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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.json-decode-notes">
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<h3 class="title">注释</h3>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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The JSON spec is not JavaScript, but a subset of JavaScript.
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</p>
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</p></blockquote>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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In the event of a failure to decode, <span class="function"><a href="json_last_error.html" class="function">json_last_error()</a></span>
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can be used to determine the exact nature of the error.
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</p>
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</p></blockquote>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.json-decode-changelog">
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<h3 class="title">更新日志</h3>
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<p class="para">
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<table class="doctable informaltable">
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<thead>
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<tr>
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<th>版本</th>
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<th>说明</th>
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</tr>
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</thead>
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<tbody class="tbody">
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<tr>
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<td>7.1.0</td>
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<td>
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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 <em>_empty_</em>.
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</td>
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</tr>
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<tr>
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<td>7.0.0</td>
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<td>
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Rejected RFC 7159 incompatible number formats - top level
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(07, 0xff, .1, -.1) and all levels ([1.], [1.e1])
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</td>
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</tr>
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<tr>
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<td>7.0.0</td>
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<td>
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An empty PHP string or value that after casting to string is an empty
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string (<em>NULL</em>, <em>FALSE</em>) results
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in JSON syntax error.
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</td>
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</tr>
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<tr>
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<td>5.6.0</td>
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<td>
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Invalid non-lowercased variants of the <em>true</em>,
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<em>false</em> and <em>null</em> literals are no
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longer accepted as valid input, and will generate warnings.
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</td>
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</tr>
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<tr>
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<td>5.4.0</td>
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<td>
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The <code class="parameter">options</code> parameter was added.
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</td>
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</tr>
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<tr>
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<td>5.3.0</td>
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<td>Added the optional <code class="parameter">depth</code>. The default recursion depth was increased from 128 to 512</td>
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</tr>
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<tr>
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<td>5.2.3</td>
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<td>The nesting limit was increased from 20 to 128</td>
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</tr>
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<tr>
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<td>5.2.1</td>
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<td>
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Added support for JSON decoding of basic types.
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</td>
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</tr>
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</tbody>
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|
||
</table>
|
||
|
||
</p>
|
||
</div>
|
||
|
||
|
||
<div class="refsect1 seealso" id="refsect1-function.json-decode-seealso">
|
||
<h3 class="title">参见</h3>
|
||
<p class="para">
|
||
<ul class="simplelist">
|
||
<li class="member"><span class="function"><a href="json_encode.html" class="function" rel="rdfs-seeAlso">json_encode()</a> - 对变量进行 JSON 编码</span></li>
|
||
<li class="member"><span class="function"><a href="json_last_error.html" class="function" rel="rdfs-seeAlso">json_last_error()</a> - 返回最后发生的错误</span></li>
|
||
</ul>
|
||
</p>
|
||
</div>
|
||
|
||
</div></div></div></body></html> |