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206 lines
13 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>返回参数列表的某一项</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.func-get-arg" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">func_get_arg</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">func_get_arg</span> — <span class="dc-title">返回参数列表的某一项</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.func-get-arg-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>func_get_arg</strong></span>
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( <span class="methodparam"><span class="type">int</span> <code class="parameter">$arg_num</code></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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从用户自定义函数的参数列表中获取某个指定的参数。
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</p>
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<p class="para">
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该函数可以配合
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<span class="function"><a href="func_get_args.html" class="function">func_get_args()</a></span> 和 <span class="function"><a href="func_num_args.html" class="function">func_num_args()</a></span>
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一起使用，从而使得用户自定义函数可以接受自定义个数的参数列表。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.func-get-arg-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">arg_num</code></dt>
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<dd>
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<p class="para">
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参数的偏移量。函数的参数是从0开始计数的。
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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.func-get-arg-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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返回指定的参数，错误则返回 <strong><code>FALSE</code></strong> 。
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.func-get-arg-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>5.3.0</td>
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<td>
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该函数可以在参数列表中使用。
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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>
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If this function is called from the outermost scope of a file
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which has been included by calling <span class="function"><a href="include.html" class="function">include</a></span>
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or <span class="function"><a href="require.html" class="function">require</a></span> from within a function in the
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calling file, it now generates a warning and returns <strong><code>FALSE</code></strong>.
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（不知道如何翻译跟好，直接参考例2即可明白）
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</td>
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</tr>
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</tbody>
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</table>
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</p>
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</div>
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<div class="refsect1 errors" id="refsect1-function.func-get-arg-errors">
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<h3 class="title">错误／异常</h3>
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<p class="para">
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当在自定义函数的外面调用的该函数的时候会发出一个警告，
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或者是当 <code class="parameter">arg_num</code> 比实际传入的参数的数目大的时候也会发出一个警告。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.func-get-arg-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-6198">
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<p><strong>Example #1 <span class="function"><strong>func_get_arg()</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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<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">foo</span><span style="color: #007700">()<br />{<br /> </span><span style="color: #0000BB">$numargs </span><span style="color: #007700">= </span><span style="color: #0000BB">func_num_args</span><span style="color: #007700">();<br /> echo </span><span style="color: #DD0000">"Number of arguments: </span><span style="color: #0000BB">$numargs</span><span style="color: #DD0000"><br />\n"</span><span style="color: #007700">;<br /> if (</span><span style="color: #0000BB">$numargs </span><span style="color: #007700">>= </span><span style="color: #0000BB">2</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">"Second argument is: " </span><span style="color: #007700">. </span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">) . </span><span style="color: #DD0000">"<br />\n"</span><span style="color: #007700">;<br /> }<br />}<br /><br /></span><span style="color: #0000BB">foo </span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">, </span><span style="color: #0000BB">2</span><span style="color: #007700">, </span><span style="color: #0000BB">3</span><span style="color: #007700">);<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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<p class="para">
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<div class="example" id="example-6199">
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<p><strong>Example #2 <span class="function"><strong>func_get_arg()</strong></span> PHP 5.3 前后对比的例子</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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test.php<br /><span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">foo</span><span style="color: #007700">() {<br /> include </span><span style="color: #DD0000">'./fga.inc'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">foo</span><span style="color: #007700">(</span><span style="color: #DD0000">'First arg'</span><span style="color: #007700">, </span><span style="color: #DD0000">'Second arg'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?><br /></span><br />fga.inc<br /><span style="color: #0000BB"><?php<br /><br />$arg </span><span style="color: #007700">= </span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</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>
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PHP 5.3 版本之前的输出：
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</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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'Second arg'
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</pre></div>
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</div>
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<div class="example-contents"><p>
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PHP 5.3 和之后的版本的输出:
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</p></div>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Warning: func_get_arg(): Called from the global scope - no function
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context in /home/torben/Desktop/code/ml/fga.inc on line 3
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false
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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-6200">
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<p><strong>Example #3 <span class="function"><strong>func_get_arg()</strong></span> example of byref and byval arguments</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: #007700">function </span><span style="color: #0000BB">byVal</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">'As passed : '</span><span style="color: #007700">, </span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)), </span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$arg </span><span style="color: #007700">= </span><span style="color: #DD0000">'baz'</span><span style="color: #007700">;<br /> echo </span><span style="color: #DD0000">'After change : '</span><span style="color: #007700">, </span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)), </span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />}<br /><br />function </span><span style="color: #0000BB">byRef</span><span style="color: #007700">(&</span><span style="color: #0000BB">$arg</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">'As passed : '</span><span style="color: #007700">, </span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)), </span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br /> </span><span style="color: #0000BB">$arg </span><span style="color: #007700">= </span><span style="color: #DD0000">'baz'</span><span style="color: #007700">;<br /> echo </span><span style="color: #DD0000">'After change : '</span><span style="color: #007700">, </span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)), </span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">$arg </span><span style="color: #007700">= </span><span style="color: #DD0000">'bar'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">byVal</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">byRef</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</span><span style="color: #007700">);<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"><br />
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As passed : 'bar'<br />
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After change : 'bar'<br />
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As passed : 'bar'<br />
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After change : 'baz'<br />
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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.func-get-arg-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">因为函数依赖于当前作用域以确定参数的细节，所以在
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5.3.0 以前的版本中不能用作函数的参数。如必须传递此值时，可将结果赋与一个变量，然后用此变量进行传递。</p></p></blockquote>
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<blockquote class="note"><p><strong class="note">Note</strong>: <p class="para">如果参数以引用方式传递，函数对该参数的任何改变将在函数返回后保留。</p></p></blockquote>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<span class="simpara">
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This function returns a copy of the passed arguments only, and does not
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account for default (non-passed) arguments.
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</span>
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</p></blockquote>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.func-get-arg-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="func_get_args.html" class="function" rel="rdfs-seeAlso">func_get_args()</a> - 返回一个包含函数参数列表的数组</span></li>
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<li class="member"><span class="function"><a href="func_num_args.html" class="function" rel="rdfs-seeAlso">func_num_args()</a> - Returns the number of arguments passed to the function</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> |