mirror of
https://github.com/fofolee/uTools-Manuals.git
synced 2025-06-18 13:57:03 +08:00
172 lines
10 KiB
HTML
172 lines
10 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
|
||
<html>
|
||
<head>
|
||
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
|
||
<title>计算数组中的单元数目，或对象中的属性个数</title>
|
||
</head>
|
||
<body class="docs"><div id="layout">
|
||
<div id="layout-content"><div id="function.count" class="refentry">
|
||
<div class="refnamediv">
|
||
<h1 class="refname">count</h1>
|
||
<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">count</span> — <span class="dc-title">计算数组中的单元数目，或对象中的属性个数</span></p>
|
||
|
||
</div>
|
||
<div class="refsect1 description" id="refsect1-function.count-description">
|
||
<h3 class="title">说明</h3>
|
||
<div class="methodsynopsis dc-description">
|
||
<span class="methodname"><strong>count</strong></span>
|
||
( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <code class="parameter">$array_or_countable</code></span>
|
||
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$mode</code><span class="initializer"> = COUNT_NORMAL</span></span>
|
||
] ) : <span class="type">int</span></div>
|
||
|
||
<p class="para rdfs-comment">
|
||
统计出数组里的所有元素的数量，或者对象里的东西。
|
||
</p>
|
||
<p class="para">
|
||
对于对象，如果安装了 <a href="ref.spl.html" class="link">SPL</a>，可以通过实现
|
||
<em>Countable</em> 接口对 <span class="function"><strong>count()</strong></span>挂钩（hook）
|
||
。该接口只有一个方法
|
||
<span class="methodname"><a href="countable.count.html" class="methodname">Countable::count()</a></span>，此方法为 <span class="function"><strong>count()</strong></span>
|
||
函数返回值。
|
||
</p>
|
||
<p class="para">
|
||
关于 PHP 中如何实现和使用数组可以参考手册中<a href="language.types.array.html" class="link">数组</a>章节中的详细描述。
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 parameters" id="refsect1-function.count-parameters">
|
||
<h3 class="title">参数</h3>
|
||
<p class="para">
|
||
<dl>
|
||
|
||
|
||
<dt>
|
||
<code class="parameter">array_or_countable</code></dt>
|
||
|
||
<dd>
|
||
|
||
<p class="para">
|
||
数组或者 <a href="class.countable.html" class="classname">Countable</a> 对象。
|
||
</p>
|
||
</dd>
|
||
|
||
|
||
|
||
<dt>
|
||
<code class="parameter">mode</code></dt>
|
||
|
||
<dd>
|
||
|
||
<p class="para">
|
||
如果可选的 <code class="parameter">mode</code> 参数设为
|
||
<strong><code>COUNT_RECURSIVE</code></strong>（或 1），<span class="function"><strong>count()</strong></span>
|
||
将递归地对数组计数。对计算多维数组的所有单元尤其有用。
|
||
</p>
|
||
<div class="caution"><strong class="caution">Caution</strong>
|
||
<p class="para">
|
||
<span class="function"><strong>count()</strong></span> 能检测递归来避免无限循环，但每次出现时会产生 <strong><code>E_WARNING</code></strong> 错误
|
||
（如果 array 不止一次包含了自身）并返回大于预期的统计数字。
|
||
</p>
|
||
</div>
|
||
</dd>
|
||
|
||
|
||
</dl>
|
||
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 returnvalues" id="refsect1-function.count-returnvalues">
|
||
<h3 class="title">返回值</h3>
|
||
<p class="para">
|
||
返回 <code class="parameter">array_or_countable</code> 中的单元数目。
|
||
|
||
如果参数既不是数组，也不是实现
|
||
<em>Countable</em> 接口的对象，将返回
|
||
<em>1</em>。
|
||
有个例外：如果
|
||
<code class="parameter">array_or_countable</code> 是 <strong><code>NULL</code></strong> 则结果是 <em>0</em>。
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 examples" id="refsect1-function.count-examples">
|
||
<h3 class="title">范例</h3>
|
||
<p class="para">
|
||
<div class="example" id="example-6090">
|
||
<p><strong>Example #1 <span class="function"><strong>count()</strong></span> 例子</strong></p>
|
||
<div class="example-contents">
|
||
<div class="phpcode"><pre><span style="color: #000000">
|
||
<span style="color: #0000BB"><?php<br />$a</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">] = </span><span style="color: #0000BB">1</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #0000BB">1</span><span style="color: #007700">] = </span><span style="color: #0000BB">3</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$a</span><span style="color: #007700">[</span><span style="color: #0000BB">2</span><span style="color: #007700">] = </span><span style="color: #0000BB">5</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">count</span><span style="color: #007700">(</span><span style="color: #0000BB">$a</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">$b</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">] = </span><span style="color: #0000BB">7</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$b</span><span style="color: #007700">[</span><span style="color: #0000BB">5</span><span style="color: #007700">] = </span><span style="color: #0000BB">9</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$b</span><span style="color: #007700">[</span><span style="color: #0000BB">10</span><span style="color: #007700">] = </span><span style="color: #0000BB">11</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">count</span><span style="color: #007700">(</span><span style="color: #0000BB">$b</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">count</span><span style="color: #007700">(</span><span style="color: #0000BB">null</span><span style="color: #007700">));<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">count</span><span style="color: #007700">(</span><span style="color: #0000BB">false</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?></span>
|
||
</span>
|
||
</pre></div>
|
||
</div>
|
||
|
||
<div class="example-contents"><p>以上例程会输出：</p></div>
|
||
<div class="example-contents screen">
|
||
<div class="cdata"><pre>
|
||
int(3)
|
||
int(3)
|
||
|
||
Warning: count(): Parameter must be an array or an object that implements Countable in … on line 12 // PHP 7.2 起
|
||
int(0)
|
||
|
||
Warning: count(): Parameter must be an array or an object that implements Countable in … on line 14 // PHP 7.2 起
|
||
int(1)
|
||
</pre></div>
|
||
</div>
|
||
</div>
|
||
</p>
|
||
<p class="para">
|
||
<div class="example" id="example-6091">
|
||
<p><strong>Example #2 递归 <span class="function"><strong>count()</strong></span> 例子</strong></p>
|
||
<div class="example-contents">
|
||
<div class="phpcode"><pre><span style="color: #000000">
|
||
<span style="color: #0000BB"><?php<br />$food </span><span style="color: #007700">= array(</span><span style="color: #DD0000">'fruits' </span><span style="color: #007700">=> array(</span><span style="color: #DD0000">'orange'</span><span style="color: #007700">, </span><span style="color: #DD0000">'banana'</span><span style="color: #007700">, </span><span style="color: #DD0000">'apple'</span><span style="color: #007700">),<br /> </span><span style="color: #DD0000">'veggie' </span><span style="color: #007700">=> array(</span><span style="color: #DD0000">'carrot'</span><span style="color: #007700">, </span><span style="color: #DD0000">'collard'</span><span style="color: #007700">, </span><span style="color: #DD0000">'pea'</span><span style="color: #007700">));<br /><br /></span><span style="color: #FF8000">// recursive count<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">count</span><span style="color: #007700">(</span><span style="color: #0000BB">$food</span><span style="color: #007700">, </span><span style="color: #0000BB">COUNT_RECURSIVE</span><span style="color: #007700">); </span><span style="color: #FF8000">// output 8<br /><br />// normal count<br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">count</span><span style="color: #007700">(</span><span style="color: #0000BB">$food</span><span style="color: #007700">); </span><span style="color: #FF8000">// output 2<br /><br /></span><span style="color: #0000BB">?></span>
|
||
</span>
|
||
</pre></div>
|
||
</div>
|
||
|
||
</div>
|
||
</p>
|
||
</div>
|
||
|
||
<div class="refsect1 changelog" id="refsect1-function.count-changelog">
|
||
<h3 class="title">更新日志</h3>
|
||
<table class="doctable informaltable">
|
||
|
||
<thead>
|
||
<tr>
|
||
<th>版本</th>
|
||
<th>说明</th>
|
||
</tr>
|
||
|
||
</thead>
|
||
|
||
<tbody class="tbody">
|
||
<tr>
|
||
<td>7.2.0</td>
|
||
<td>
|
||
当无效的 countable 类型传递给 <code class="parameter">array_or_countable</code> 参数时，<span class="function"><strong>count()</strong></span> 会产生警告。
|
||
</td>
|
||
</tr>
|
||
|
||
</tbody>
|
||
|
||
</table>
|
||
|
||
</div>
|
||
|
||
|
||
<div class="refsect1 seealso" id="refsect1-function.count-seealso">
|
||
<h3 class="title">参见</h3>
|
||
<p class="para">
|
||
<ul class="simplelist">
|
||
<li class="member"><span class="function"><a href="is_array.html" class="function" rel="rdfs-seeAlso">is_array()</a> - 检测变量是否是数组</span></li>
|
||
<li class="member"><span class="function"><a href="isset.html" class="function" rel="rdfs-seeAlso">isset()</a> - 检测变量是否已设置并且非 NULL</span></li>
|
||
<li class="member"><span class="function"><a href="empty.html" class="function" rel="rdfs-seeAlso">empty()</a> - 检查一个变量是否为空</span></li>
|
||
<li class="member"><span class="function"><a href="strlen.html" class="function" rel="rdfs-seeAlso">strlen()</a> - 获取字符串长度</span></li>
|
||
</ul>
|
||
</p>
|
||
</div>
|
||
|
||
</div></div></div></body></html> |