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<!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>获取变量的整数值</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.intval" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">intval</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">intval</span> — <span class="dc-title">获取变量的整数值</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.intval-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>intval</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">$var</code></span>
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[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$base</code><span class="initializer"> = 10</span></span>
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] ) : <span class="type">int</span></div>
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<p class="para rdfs-comment">
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通过使用指定的进制 <code class="parameter">base</code> 转换（默认是十进制），返回变量 <code class="parameter">var</code>
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的 <span class="type"><a href="language.types.integer.html" class="type integer">integer</a></span> 数值。
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<span class="function"><strong>intval()</strong></span> 不能用于 object，否则会产生 <strong><code>E_NOTICE</code></strong> 错误并返回 1。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.intval-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">var</code></dt>
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<dd>
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<p class="para">
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要转换成 integer 的数量值
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</p>
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</dd>
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<dt>
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<code class="parameter">base</code></dt>
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<dd>
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<p class="para">
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转化所使用的进制
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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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如果 <code class="parameter">base</code> 是 0，通过检测 <code class="parameter">var</code> 的格式来决定使用的进制：
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<ul class="itemizedlist">
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<li class="listitem">
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<span class="simpara">
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如果字符串包括了 "0x" (或 "0X") 的前缀，使用 16 进制 (hex)；否则，
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</span>
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</li>
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<li class="listitem">
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<span class="simpara">
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如果字符串以 "0" 开始，使用 8 进制(octal)；否则，
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</span>
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</li>
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<li class="listitem">
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<span class="simpara">
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将使用 10 进制 (decimal)。
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</span>
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</li>
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</ul>
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</p>
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</p></blockquote>
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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.intval-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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成功时返回 <code class="parameter">var</code> 的 integer 值，失败时返回 0。
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空的 array 返回 0，非空的 array 返回 1。
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</p>
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<p class="para">
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最大的值取决于操作系统。 32 位系统最大带符号的 integer 范围是 -2147483648 到 2147483647。举例，在这样的系统上， <em>intval('1000000000000')</em> 会返回
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2147483647。64 位系统上，最大带符号的 integer 值是
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9223372036854775807。
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</p>
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<p class="para">
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字符串有可能返回 0，虽然取决于字符串最左侧的字符。
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使用
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<a href="language.types.integer.html#language.types.integer.casting" class="link">整型转换</a>
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的共同规则。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.intval-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-6360">
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<p><strong>Example #1 <span class="function"><strong>intval()</strong></span> 例子</strong></p>
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<div class="example-contents"><p>
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下面的例子运行于 32 位系统上。
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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 /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">42</span><span style="color: #007700">); </span><span style="color: #FF8000">// 42<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">4.2</span><span style="color: #007700">); </span><span style="color: #FF8000">// 4<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #DD0000">'42'</span><span style="color: #007700">); </span><span style="color: #FF8000">// 42<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #DD0000">'+42'</span><span style="color: #007700">); </span><span style="color: #FF8000">// 42<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #DD0000">'-42'</span><span style="color: #007700">); </span><span style="color: #FF8000">// -42<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">042</span><span style="color: #007700">); </span><span style="color: #FF8000">// 34<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #DD0000">'042'</span><span style="color: #007700">); </span><span style="color: #FF8000">// 42<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">1e10</span><span style="color: #007700">); </span><span style="color: #FF8000">// 1410065408<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #DD0000">'1e10'</span><span style="color: #007700">); </span><span style="color: #FF8000">// 1<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">0x1A</span><span style="color: #007700">); </span><span style="color: #FF8000">// 26<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">42000000</span><span style="color: #007700">); </span><span style="color: #FF8000">// 42000000<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">420000000000000000000</span><span style="color: #007700">); </span><span style="color: #FF8000">// 0<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #DD0000">'420000000000000000000'</span><span style="color: #007700">); </span><span style="color: #FF8000">// 2147483647<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #0000BB">42</span><span style="color: #007700">, </span><span style="color: #0000BB">8</span><span style="color: #007700">); </span><span style="color: #FF8000">// 42<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(</span><span style="color: #DD0000">'42'</span><span style="color: #007700">, </span><span style="color: #0000BB">8</span><span style="color: #007700">); </span><span style="color: #FF8000">// 34<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(array()); </span><span style="color: #FF8000">// 0<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">intval</span><span style="color: #007700">(array(</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: #FF8000">// 1<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 notes" id="refsect1-function.intval-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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除非 <code class="parameter">var</code> 是一个字符串，否则 <code class="parameter">base</code> 不会起作用。
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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.intval-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>5.1.0</td>
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<td>
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当传入的 <code class="parameter">var</code> 是 object，将会抛出 <strong><code>E_NOTICE</code></strong> 并返回 1。
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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 seealso" id="refsect1-function.intval-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="boolval.html" class="function" rel="rdfs-seeAlso">boolval()</a> - 获取变量的布尔值</span></li>
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<li class="member"><span class="function"><a href="floatval.html" class="function" rel="rdfs-seeAlso">floatval()</a> - 获取变量的浮点值</span></li>
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<li class="member"><span class="function"><a href="strval.html" class="function" rel="rdfs-seeAlso">strval()</a> - 获取变量的字符串值</span></li>
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<li class="member"><span class="function"><a href="settype.html" class="function" rel="rdfs-seeAlso">settype()</a> - 设置变量的类型</span></li>
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<li class="member"><span class="function"><a href="is_numeric.html" class="function" rel="rdfs-seeAlso">is_numeric()</a> - 检测变量是否为数字或数字字符串</span></li>
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<li class="member"><a href="language.types.type_juggling.html" class="link">类型转换的判别</a></li>
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<li class="member"><a href="ref.bc.html" class="link">BCMath 任意精度数学函数</a></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> |