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94 lines
3.8 KiB
HTML
94 lines
3.8 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>判断是否为合法数值</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-nan" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">is_nan</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_nan</span> — <span class="dc-title">判断是否为合法数值</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.is-nan-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_nan</strong></span>
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( <span class="methodparam"><span class="type">float</span> <code class="parameter">$val</code></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">val</code> 为“非数值”，例如
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<em>acos(1.01)</em> 的结果，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 parameters" id="refsect1-function.is-nan-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">val</code></dt>
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<dd>
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<p class="para">
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要检查的值
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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-nan-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 <code class="parameter">val</code> 不是一个数字（not a number）返回 <strong><code>TRUE</code></strong>，否则返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.is-nan-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-4131">
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<p><strong>Example #1 <span class="function"><strong>is_nan()</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">// Invalid calculation, will return a <br />// NaN value<br /></span><span style="color: #0000BB">$nan </span><span style="color: #007700">= </span><span style="color: #0000BB">acos</span><span style="color: #007700">(</span><span style="color: #0000BB">8</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">$nan</span><span style="color: #007700">, </span><span style="color: #0000BB">is_nan</span><span style="color: #007700">(</span><span style="color: #0000BB">$nan</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">
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<div class="cdata"><pre>
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float(NAN)
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bool(true)
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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-nan-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="is_finite.html" class="function" rel="rdfs-seeAlso">is_finite()</a> - 判断是否为有限值</span></li>
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<li class="member"><span class="function"><a href="is_infinite.html" class="function" rel="rdfs-seeAlso">is_infinite()</a> - 判断是否为无限值</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> |