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167 lines
6.9 KiB
HTML
167 lines
6.9 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>如果对象属于该类或该类是此对象的父类则返回 TRUE</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.is-a" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">is_a</h1>
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<p class="verinfo">(PHP 4 >= 4.2.0, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">is_a</span> — <span class="dc-title">如果对象属于该类或该类是此对象的父类则返回 <strong><code>TRUE</code></strong></span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.is-a-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>is_a</strong></span>
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( <span class="methodparam"><span class="type">object</span> <code class="parameter">$object</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$class_name</code></span>
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[, <span class="methodparam"><span class="type">bool</span> <code class="parameter">$allow_string</code><span class="initializer"> = <strong><code>FALSE</code></strong></span></span>
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] ) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">
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如果 <code class="parameter">object</code> 是该类或该类是此对象的父类。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.is-a-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">object</code></dt>
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<dd>
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<p class="para">
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The tested object
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</p>
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</dd>
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<dt>
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<code class="parameter">class_name</code></dt>
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<dd>
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<p class="para">
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The class name
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</p>
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</dd>
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<dt>
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<code class="parameter">allow_string</code></dt>
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<dd>
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<p class="para">
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If this parameter set to <strong><code>FALSE</code></strong>, string class name as <code class="parameter">object</code>
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is not allowed. This also prevents from calling autoloader if the class doesn't exist.
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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.is-a-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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Returns <strong><code>TRUE</code></strong> if the object is of this class or has this class as one of
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its parents, <strong><code>FALSE</code></strong> otherwise.
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</p>
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</div>
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<div class="refsect1 changelog" id="refsect1-function.is-a-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>5.3.9</td>
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<td>
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Added <code class="parameter">allow_string</code> parameter
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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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This function is no longer deprecated, and will therefore
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no longer throw <strong><code>E_STRICT</code></strong> warnings.
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</td>
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</tr>
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<tr>
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<td>5.0.0</td>
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<td>
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This function became deprecated in favour of the
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<a href="language.operators.type.html" class="link">instanceof</a>
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operator. Calling this function will result in an
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<strong><code>E_STRICT</code></strong> warning.
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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 examples" id="refsect1-function.is-a-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-6147">
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<p><strong>Example #1 <span class="function"><strong>is_a()</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: #FF8000">// define a class<br /></span><span style="color: #007700">class </span><span style="color: #0000BB">WidgetFactory<br /></span><span style="color: #007700">{<br /> var </span><span style="color: #0000BB">$oink </span><span style="color: #007700">= </span><span style="color: #DD0000">'moo'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #FF8000">// create a new object<br /></span><span style="color: #0000BB">$WF </span><span style="color: #007700">= new </span><span style="color: #0000BB">WidgetFactory</span><span style="color: #007700">();<br /><br />if (</span><span style="color: #0000BB">is_a</span><span style="color: #007700">(</span><span style="color: #0000BB">$WF</span><span style="color: #007700">, </span><span style="color: #DD0000">'WidgetFactory'</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"yes, \$WF is still a WidgetFactory\n"</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>
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<div class="example" id="example-6148">
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<p><strong>Example #2 在 PHP 5 中使用 <em class="emphasis">instanceof</em> 运算符</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">if (</span><span style="color: #0000BB">$WF </span><span style="color: #007700">instanceof </span><span style="color: #0000BB">WidgetFactory</span><span style="color: #007700">) {<br /> echo </span><span style="color: #DD0000">'Yes, $WF is a WidgetFactory'</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>
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</p>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.is-a-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="get_class.html" class="function" rel="rdfs-seeAlso">get_class()</a> - 返回对象的类名</span></li>
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<li class="member"><span class="function"><a href="get_parent_class.html" class="function" rel="rdfs-seeAlso">get_parent_class()</a> - 返回对象或类的父类名</span></li>
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<li class="member"><span class="function"><a href="is_subclass_of.html" class="function" rel="rdfs-seeAlso">is_subclass_of()</a> - 如果此对象是该类的子类，则返回 TRUE</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> |