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165 lines
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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>使用用户自定义函数对数组中的每个元素做回调处理</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.array-walk" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">array_walk</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">array_walk</span> — <span class="dc-title">使用用户自定义函数对数组中的每个元素做回调处理</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.array-walk-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>array_walk</strong></span>
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( <span class="methodparam"><span class="type">array</span> <code class="parameter reference">&$array</code></span>
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, <span class="methodparam"><span class="type"><a href="language.types.callable.html" class="type callable">callable</a></span> <code class="parameter">$callback</code></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">$userdata</code><span class="initializer"> = <strong><code>NULL</code></strong></span></span>
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] ) : <span class="type">bool</span></div>
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<p class="simpara">
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将用户自定义函数 <code class="parameter">funcname</code> 应用到
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<code class="parameter">array</code> 数组中的每个单元。
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</p>
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<p class="para">
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<span class="function"><strong>array_walk()</strong></span> 不会受到 <code class="parameter">array</code>
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内部数组指针的影响。<span class="function"><strong>array_walk()</strong></span>
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会遍历整个数组而不管指针的位置。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.array-walk-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">array</code></dt>
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<dd>
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<p class="para">
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输入的数组。
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</p>
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</dd>
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<dt>
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<code class="parameter">callback</code></dt>
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<dd>
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<p class="para">
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典型情况下
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<code class="parameter">callback</code> 接受两个参数。<code class="parameter">array</code>
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参数的值作为第一个，键名作为第二个。
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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">callback</code> 需要直接作用于数组中的值，则给
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<code class="parameter">callback</code> 的第一个参数指定为<a href="language.references.html" class="link">引用</a>。这样任何对这些单元的改变也将会改变原始数组本身。
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</p>
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</p></blockquote>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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参数数量超过预期，传入内置函数 (例如 <span class="function"><a href="strtolower.html" class="function">strtolower()</a></span>)，
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将抛出警告，所以不适合当做 <code class="parameter">funcname</code>。
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</p>
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</p></blockquote>
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<p class="para">
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只有 <code class="parameter">array</code> 的值才可以被改变，用户不应在回调函数中改变该数组本身的结构。例如增加/删除单元，unset
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单元等等。如果 <span class="function"><strong>array_walk()</strong></span>
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作用的数组改变了，则此函数的的行为未经定义，且不可预期。
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</p>
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</dd>
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<dt>
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<code class="parameter">userdata</code></dt>
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<dd>
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<p class="para">
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如果提供了可选参数
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<code class="parameter">userdata</code>，将被作为第三个参数传递给
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callback <code class="parameter">funcname</code>。
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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.array-walk-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 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 errors" id="refsect1-function.array-walk-errors">
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<h3 class="title">错误／异常</h3>
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<p class="para">
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如果 <code class="parameter">callback</code> 函数需要的参数比给出的多，则每次
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<span class="function"><strong>array_walk()</strong></span> 调用 <code class="parameter">callback</code>
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时都会产生一个 <a href="errorfunc.constants.html" class="link">E_WARNING</a>
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级的错误。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.array-walk-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-6082">
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<p><strong>Example #1 <span class="function"><strong>array_walk()</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 />$fruits </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"d" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"lemon"</span><span style="color: #007700">, </span><span style="color: #DD0000">"a" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"orange"</span><span style="color: #007700">, </span><span style="color: #DD0000">"b" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"banana"</span><span style="color: #007700">, </span><span style="color: #DD0000">"c" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"apple"</span><span style="color: #007700">);<br /><br />function </span><span style="color: #0000BB">test_alter</span><span style="color: #007700">(&</span><span style="color: #0000BB">$item1</span><span style="color: #007700">, </span><span style="color: #0000BB">$key</span><span style="color: #007700">, </span><span style="color: #0000BB">$prefix</span><span style="color: #007700">)<br />{<br /> </span><span style="color: #0000BB">$item1 </span><span style="color: #007700">= </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$prefix</span><span style="color: #DD0000">: </span><span style="color: #0000BB">$item1</span><span style="color: #DD0000">"</span><span style="color: #007700">;<br />}<br /><br />function </span><span style="color: #0000BB">test_print</span><span style="color: #007700">(</span><span style="color: #0000BB">$item2</span><span style="color: #007700">, </span><span style="color: #0000BB">$key</span><span style="color: #007700">)<br />{<br /> echo </span><span style="color: #DD0000">"</span><span style="color: #0000BB">$key</span><span style="color: #DD0000">. </span><span style="color: #0000BB">$item2</span><span style="color: #DD0000"><br />\n"</span><span style="color: #007700">;<br />}<br /><br />echo </span><span style="color: #DD0000">"Before ...:\n"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">array_walk</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruits</span><span style="color: #007700">, </span><span style="color: #DD0000">'test_print'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">array_walk</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruits</span><span style="color: #007700">, </span><span style="color: #DD0000">'test_alter'</span><span style="color: #007700">, </span><span style="color: #DD0000">'fruit'</span><span style="color: #007700">);<br />echo </span><span style="color: #DD0000">"... and after:\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">array_walk</span><span style="color: #007700">(</span><span style="color: #0000BB">$fruits</span><span style="color: #007700">, </span><span style="color: #DD0000">'test_print'</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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Before ...:
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d. lemon
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a. orange
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b. banana
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c. apple
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... and after:
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d. fruit: lemon
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a. fruit: orange
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b. fruit: banana
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c. fruit: apple
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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.array-walk-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="array_walk_recursive.html" class="function" rel="rdfs-seeAlso">array_walk_recursive()</a> - 对数组中的每个成员递归地应用用户函数</span></li>
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<li class="member"><span class="function"><a href="iterator_apply.html" class="function" rel="rdfs-seeAlso">iterator_apply()</a> - 为迭代器中每个元素调用一个用户自定义函数</span></li>
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<li class="member"><span class="function"><a href="list.html" class="function" rel="rdfs-seeAlso">list()</a> - 把数组中的值赋给一组变量</span></li>
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<li class="member"><span class="function"><a href="each.html" class="function" rel="rdfs-seeAlso">each()</a> - 返回数组中当前的键／值对并将数组指针向前移动一步</span></li>
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<li class="member"><span class="function"><a href="call_user_func_array.html" class="function" rel="rdfs-seeAlso">call_user_func_array()</a> - 调用回调函数，并把一个数组参数作为回调函数的参数</span></li>
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<li class="member"><span class="function"><a href="array_map.html" class="function" rel="rdfs-seeAlso">array_map()</a> - 为数组的每个元素应用回调函数</span></li>
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<li class="member"><a href="language.pseudo-types.html#language.types.callback" class="link">callback</a> 类型的信息</li>
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<li class="member"><a href="control_structures.foreach.html" class="link">foreach</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> |