在 PHP 中实现回调函数-php教程-PHP中文网

在PHP中，回调函数是一种常见的编程技术，能够增强代码的灵活性和可复用性。通过回调函数，我们可以将函数作为参数传递给其他函数，在特定的条件下被调用。这种方式使得代码结构更加清晰，并且可以根据需要动态地改变函数的行为。本文将介绍在PHP中实现回调函数的方法，以及如何有效地利用回调函数来简化代码逻辑和提高代码的可维护性。php小编百草将为您详细讲解如何使用回调函数，让您轻松掌握这一重要的编程技术。

在 php 中创建一个 `callback` 函数并使用 `call_user_func` 执行

我们创建了一个名为 testFunct<code>testFunct<strong class="keylink">io</strong>n() 的 callback 函数，并使用 call_user_func()ion() 的 callback 函数，并使用 call_user_func() 方法通过将函数名称作为字符串

传递给该方法来执行它。

例子：

<code>
<code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#666"><?</span>php
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">testFunction</span>() {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"Testing Callback </span><span style="color:#b62;font-weight:bold">\n</span><span style="color:#ba2121">"</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">// Standard callback
</span></span></span><span style="display:flex;"><span>call_user_func(<span style="color:#ba2121">&#39;testFunction&#39;</span>);
</span></span><span style="display:flex;"><span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

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输出：

<code>
<code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>Testing Callback
</span></span></code></code>

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`callback` 函数并使用 `array_map` 在 PHP 中创建一个

方法执行

array_map 方法执行 callback 函数。这将使用传递给 array_map() 我们使用

函数的相应数据执行该方法。

例子：

<code>
<code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#666"><?</span>php
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">length_callback</span>(<span style="color:#19177c">$item</span>) {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">return</span> strlen(<span style="color:#19177c">$item</span>);
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span><span style="color:#19177c">$strings</span> <span style="color:#666">=</span> [<span style="color:#ba2121">"Kevin Amayi"</span>, <span style="color:#ba2121">"Programmer"</span>, <span style="color:#ba2121">"N<strong class="keylink">ai</strong>robi"</span>, <span style="color:#ba2121">"Data Science"</span>];
</span></span><span style="display:flex;"><span><span style="color:#19177c">$lengths</span> <span style="color:#666">=</span> array_map(<span style="color:#ba2121">"length_callback"</span>, <span style="color:#19177c">$strings</span>);
</span></span><span style="display:flex;"><span>print_r(<span style="color:#19177c">$lengths</span>);
</span></span><span style="display:flex;"><span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

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输出：

<code>
<code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>Array ( [0] => 11 [1] => 10 [2] => 7 [3] => 12 )
</span></span></code></code>

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在 PHP 中实现多个回调函数并使用用户定义的函数执行它们

testCallBacks() 的用户定义函数执行两个名为 name 和 age 的 callback 我们将使用名为

函数，将函数的名称作为字符串绕过用户定义的函数。

例子：

<code>
<code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#666"><?</span>php
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">name</span>(<span style="color:#19177c">$str</span>) {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">return</span> <span style="color:#19177c">$str</span> <span style="color:#666">.</span> <span style="color:#ba2121">" Kevin"</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">age</span>(<span style="color:#19177c">$str</span>) {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">return</span> <span style="color:#19177c">$str</span> <span style="color:#666">.</span> <span style="color:#ba2121">" Kevin 23 "</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">testCallBacks</span>(<span style="color:#19177c">$str</span>, <span style="color:#19177c">$f<strong class="keylink">ORM</strong>at</span>) {
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">// Calling the $format callback function
</span></span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$format</span>(<span style="color:#19177c">$str</span>)<span style="color:#666">.</span><span style="color:#ba2121">"<br>"</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">// Pass "name" and "age" as callback functions to testCallBacks()
</span></span></span><span style="display:flex;"><span>testCallBacks(<span style="color:#ba2121">" Hello"</span>, <span style="color:#ba2121">"name"</span>);
</span></span><span style="display:flex;"><span>testCallBacks(<span style="color:#ba2121">" Hello"</span>, <span style="color:#ba2121">"age"</span>);
</span></span><span style="display:flex;"><span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

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输出：

<code>
<code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>Hello Kevin
</span></span><span style="display:flex;"><span>Hello Kevin 23
</span></span></code></code>

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`static` 类和 `call_user_func` 将 `static` 方法实现为 `callback` 在 PHP 中使用

函数

static 方法创建两个 static 类，并使用 call_user_func() 方法将它们作为 callbacks 我们将使用

执行。

<code>
<code class="language-php hljs" data-lang="php"><span style="display:flex;"><span><span style="color:#666"><?</span>php
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">// Sample Person class
</span></span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">class</span> <span style="color:#00f;font-weight:bold">Person</span> {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">static</span> <span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">walking</span>() {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"I am moving my feet <br>"</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">//child class extends the parent Person class
</span></span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">class</span> <span style="color:#00f;font-weight:bold">Student</span> <span style="color:#008000;font-weight:bold">extends</span> Person {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">static</span> <span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">walking</span>() {
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"student is moving his/her feet <br>"</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">// Parent class Static method callbacks
</span></span></span><span style="display:flex;"><span>call_user_func(<span style="color:#008000;font-weight:bold">array</span>(<span style="color:#ba2121">'Person'</span>, <span style="color:#ba2121">'walking'</span>));
</span></span><span style="display:flex;"><span>call_user_func(<span style="color:#ba2121">'Person::walking'</span>);
</span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">// Child class Static method callback
</span></span></span><span style="display:flex;"><span>call_user_func(<span style="color:#008000;font-weight:bold">array</span>(<span style="color:#ba2121">'Student'</span>, <span style="color:#ba2121">'Student::walking'</span>));
</span></span><span style="display:flex;"><span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

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输出：🎜

<code>
<code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>I am moving my feet
</span></span><span style="display:flex;"><span>I am moving my feet
</span></span><span style="display:flex;"><span>student is moving his/her feet
</span></span></code></code>

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