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153 lines
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153 lines
8.3 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>以易于理解的格式打印变量。</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.print-r" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">print_r</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">print_r</span> — <span class="dc-title">
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以易于理解的格式打印变量。
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</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.print-r-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>print_r</strong></span>
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( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$expression</code></span>
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[, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$return</code><span class="initializer"> = <strong><code>FALSE</code></strong></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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<span class="function"><strong>print_r()</strong></span> 以人类易读的格式显示一个变量的信息。
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</p>
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<p class="para">
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<span class="function"><strong>print_r()</strong></span>、
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<span class="function"><a href="var_dump.html" class="function">var_dump()</a></span>、
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<span class="function"><a href="var_export.html" class="function">var_export()</a></span>
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都会显示对象 protected 和 private 的属性。
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Class 的静态属性（static） 则不会显示。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.print-r-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">expression</code></dt>
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<dd>
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<p class="para">
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要打印的表达式。
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</p>
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</dd>
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<dt>
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<code class="parameter">return</code></dt>
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<dd>
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<p class="para">
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想要获取 <span class="function"><strong>print_r()</strong></span> 输出的内容，使用 <code class="parameter">return</code> 参数。
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当此参数为 <strong><code>TRUE</code></strong>，<span class="function"><strong>print_r()</strong></span> 会直接返回信息，而不是输出。
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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.print-r-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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如果输入的内容是 <span class="type"><a href="language.types.string.html" class="type string">string</a></span>、 <span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span> 或 <span class="type"><a href="language.types.float.html" class="type float">float</a></span>，会直接输出值本身。
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如果输入的内容是 <span class="type"><a href="language.types.array.html" class="type array">array</a></span>，展示的格式会显示数组的键和包含的元素。<span class="type"><a href="language.types.object.html" class="type object">object</a></span> 也类似。
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</p>
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<p class="para">
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当 <code class="parameter">return</code> 参数设置成 <strong><code>TRUE</code></strong>，本函数会返回 <span class="type"><a href="language.types.string.html" class="type string">string</a></span> 格式。否则返回 <strong><code>TRUE</code></strong>。
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.print-r-notes">
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<h3 class="title">注释</h3>
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<blockquote class="note"><p><strong class="note">Note</strong>: <p class="para">当使用了<code class="parameter">return</code>
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参数时，本函数使用其内部输出缓冲，因此不能在
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<span class="function"><a href="ob_start.html" class="function">ob_start()</a></span> 回调函数的内部使用。</p></p></blockquote>
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</div>
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<div class="refsect1 examples" id="refsect1-function.print-r-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-6367">
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<p><strong>Example #1 <span class="function"><strong>print_r()</strong></span> 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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<pre><br /><span style="color: #0000BB"><?php<br />$a </span><span style="color: #007700">= array (</span><span style="color: #DD0000">'a' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'apple'</span><span style="color: #007700">, </span><span style="color: #DD0000">'b' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'banana'</span><span style="color: #007700">, </span><span style="color: #DD0000">'c' </span><span style="color: #007700">=> array (</span><span style="color: #DD0000">'x'</span><span style="color: #007700">, </span><span style="color: #DD0000">'y'</span><span style="color: #007700">, </span><span style="color: #DD0000">'z'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">print_r </span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?><br /></span></pre></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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<pre>
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Array
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(
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[a] => apple
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[b] => banana
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[c] => Array
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(
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[0] => x
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[1] => y
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[2] => z
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)
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)
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</pre>
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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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<p class="para">
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<div class="example" id="example-6368">
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<p><strong>Example #2 <code class="parameter">return</code> 参数的例子</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 />$b </span><span style="color: #007700">= array (</span><span style="color: #DD0000">'m' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'monkey'</span><span style="color: #007700">, </span><span style="color: #DD0000">'foo' </span><span style="color: #007700">=> </span><span style="color: #DD0000">'bar'</span><span style="color: #007700">, </span><span style="color: #DD0000">'x' </span><span style="color: #007700">=> array (</span><span style="color: #DD0000">'x'</span><span style="color: #007700">, </span><span style="color: #DD0000">'y'</span><span style="color: #007700">, </span><span style="color: #DD0000">'z'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">$results </span><span style="color: #007700">= </span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$b</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">); </span><span style="color: #FF8000">// $results 包含了 print_r 的输出<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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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.print-r-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="ob_start.html" class="function" rel="rdfs-seeAlso">ob_start()</a> - 打开输出控制缓冲</span></li>
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<li class="member"><span class="function"><a href="var_dump.html" class="function" rel="rdfs-seeAlso">var_dump()</a> - 打印变量的相关信息</span></li>
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<li class="member"><span class="function"><a href="var_export.html" class="function" rel="rdfs-seeAlso">var_export()</a> - 输出或返回一个变量的字符串表示</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |