Konstruktor in PHP-PHP-Tutorial-php.cn

Der PHP-Editor Xiaoxin gibt Ihnen eine detaillierte Analyse des Konstruktors in PHP. Ein Konstruktor ist eine Methode, die automatisch aufgerufen wird, wenn ein Objekt instanziiert wird, um die Eigenschaften des Objekts zu initialisieren. Über den Konstruktor können Sie beim Erstellen eines Objekts Parameter übergeben und Eigenschaften Werte zuweisen, wodurch die Lesbarkeit und Wiederverwendbarkeit des Codes verbessert wird. Der Name des Konstruktors ist derselbe wie der Klassenname und es ist nicht erforderlich, ihn manuell aufzurufen, was eine einheitliche Verwaltung und Wartung des Codes erleichtert. In PHP sind Konstruktoren ein wichtiger Bestandteil der objektorientierten Programmierung. Ein tiefes Verständnis und eine rationelle Anwendung von Konstruktoren können die Qualität und Effizienz von Code verbessern.

Wir werden diese Funktion auch verwenden, um die Eigenschaften des Objekts in der Klasse mit den angegebenen Parametern zu initialisieren.

Abschließend sehen wir uns an, wie man eine Funktion in 子类中启动对象并在两个类都有单独的构造函数时调用父类 erstellt.

Verwenden Sie den php-Konstruktor, um die Eigenschaften von Objekten in der Klasse zu initialisieren

Im folgenden Beispiel erstellen wir eine Klasse Student 并使用 __construct 函数为 new Student und weisen ihre Eigenschaften zu.

__construct 函数减少了与使用函数 set_name() Relevante Anzahl an Codes.

<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></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></span><span style="display:flex;"><span>	<span style="color:#408080;font-style:italic">// Define the attributes of your class
</span></span></span><span style="display:flex;"><span>	
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#19177c">$name</span>;
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#19177c">$em<strong class="keylink">ai</strong>l</span>;
</span></span><span style="display:flex;"><span><span style="color:#408080;font-style:italic">// Initialize the properties of the object you want to create in this class
</span></span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">funct<strong class="keylink">io</strong>n</span> __construct(<span style="color:#19177c">$name</span>, <span style="color:#19177c">$email</span>) {
</span></span><span style="display:flex;"><span>	<span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">name</span> <span style="color:#666">=</span> <span style="color:#19177c">$name</span>;
</span></span><span style="display:flex;"><span>	<span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">email</span> <span style="color:#666">=</span> <span style="color:#19177c">$email</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">get_name</span>() {
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">return</span> <span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">name</span>;
</span></span><span style="display:flex;"><span>}
</span></span><span style="display:flex;"><span>
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">function</span> <span style="color:#00f">get_email</span>() {
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">return</span> <span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">email</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:#19177c">$obj</span> <span style="color:#666">=</span> <span style="color:#008000;font-weight:bold">new</span> Student(<span style="color:#ba2121">"John"</span>, <span style="color:#ba2121">"john567@gmail.com"</span>);
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$obj</span><span style="color:#666">-></span><span style="color:#7d9029">get_name</span>();
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"<br>"</span>;
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$obj</span><span style="color:#666">-></span><span style="color:#7d9029">get_email</span>();
</span></span><span style="display:flex;"><span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

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Ausgabe:

<code>
<code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>John
</span></span><span style="display:flex;"><span>john567@gmail.com
</span></span></code></code>

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Initialisieren Sie die Eigenschaften von `Object with Parameters` in der Klasse mit dem PHP-Konstruktor

Im folgenden Beispielcode erstellen wir eine Klassenfunktion

, um die Eigenschaften und Parameter des von uns erstellten Objekts bereitzustellen. Military 并使用 __construct

<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">class</span> <span style="color:#00f;font-weight:bold">Military</span> {
</span></span><span style="display:flex;"><span>	<span style="color:#408080;font-style:italic">// Define the attributes of the class &#39;Military&#39;
</span></span></span><span style="display:flex;"><span>	
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#19177c">$name</span>;
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#19177c">$rank</span>;
</span></span><span style="display:flex;"><span>	
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">function</span> __construct(<span style="color:#19177c">$name</span>, <span style="color:#19177c">$rank</span>){
</span></span><span style="display:flex;"><span>		<span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">name</span> <span style="color:#666">=</span> <span style="color:#19177c">$name</span>;
</span></span><span style="display:flex;"><span>		<span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">rank</span> <span style="color:#666">=</span> <span style="color:#19177c">$rank</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">show_detail</span>() {
</span></span><span style="display:flex;"><span>		<span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">name</span><span style="color:#666">.</span><span style="color:#ba2121">" : "</span>;
</span></span><span style="display:flex;"><span>		<span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"Your Rank is "</span><span style="color:#666">.</span><span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">rank</span><span style="color:#666">.</span><span style="color:#ba2121">"</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></span><span style="display:flex;"><span><span style="color:#19177c">$person_obj</span> <span style="color:#666">=</span> <span style="color:#008000;font-weight:bold">new</span> Military(<span style="color:#ba2121">"Michael"</span>, <span style="color:#ba2121">"General"</span>);
</span></span><span style="display:flex;"><span><span style="color:#19177c">$person_obj</span><span style="color:#666">-></span><span style="color:#7d9029">show_detail</span>();
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"<br>"</span>;
</span></span><span style="display:flex;"><span><span style="color:#19177c">$person2</span> <span style="color:#666">=</span> <span style="color:#008000;font-weight:bold">new</span> Military(<span style="color:#ba2121">"Fred"</span>, <span style="color:#ba2121">"Commander"</span>);
</span></span><span style="display:flex;"><span><span style="color:#19177c">$person2</span><span style="color:#666">-></span><span style="color:#7d9029">show_detail</span>();
</span></span><span style="display:flex;"><span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

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Ausgabe:

<code>
<code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>Michael : Your Rank is General
</span></span><span style="display:flex;"><span>Fred : Your Rank is Commander
</span></span></code></code>

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Starten Sie in PHP ein Objekt in der untergeordneten Klasse und rufen Sie den Konstruktor

der übergeordneten Klasse auf, wenn beide Klassen über einen Konstruktor Individual verfügen

<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">class</span> <span style="color:#00f;font-weight:bold">Student</span>
</span></span><span style="display:flex;"><span>{
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#19177c">$name</span>;
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#008000;font-weight:bold">function</span> __construct(<span style="color:#19177c">$name</span>)
</span></span><span style="display:flex;"><span>	{
</span></span><span style="display:flex;"><span>		<span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">name</span> <span style="color:#666">=</span> <span style="color:#19177c">$name</span>;
</span></span><span style="display:flex;"><span>	}
</span></span><span style="display:flex;"><span>}<span style="color:#008000;font-weight:bold">class</span> <span style="color:#00f;font-weight:bold">Identity</span> <span style="color:#008000;font-weight:bold">extends</span> Student
</span></span><span style="display:flex;"><span>{
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#19177c">$identity_id</span>;
</span></span><span style="display:flex;"><span>	
</span></span><span style="display:flex;"><span>	<span style="color:#008000;font-weight:bold">public</span> <span style="color:#008000;font-weight:bold">function</span> __construct(<span style="color:#19177c">$name</span>, <span style="color:#19177c">$identity_id</span>)
</span></span><span style="display:flex;"><span>	{
</span></span><span style="display:flex;"><span>		<span style="color:#008000;font-weight:bold">parent</span><span style="color:#666">::</span><span style="color:#7d9029">__construct</span>(<span style="color:#19177c">$name</span>);
</span></span><span style="display:flex;"><span>		<span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">identity_id</span> <span style="color:#666">=</span> <span style="color:#19177c">$identity_id</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">show_detail</span>() {
</span></span><span style="display:flex;"><span>		<span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">name</span><span style="color:#666">.</span><span style="color:#ba2121">" : "</span>;
</span></span><span style="display:flex;"><span>		<span style="color:#008000;font-weight:bold">echo</span> <span style="color:#ba2121">"Your Id Number is "</span><span style="color:#666">.</span><span style="color:#19177c">$this</span><span style="color:#666">-></span><span style="color:#7d9029">identity_id</span><span style="color:#666">.</span><span style="color:#ba2121">"</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></span><span style="display:flex;"><span><span style="color:#19177c">$obj</span> <span style="color:#666">=</span> <span style="color:#008000;font-weight:bold">new</span> Identity(<span style="color:#ba2121">'Alice'</span>, <span style="color:#ba2121">'1036398'</span>);
</span></span><span style="display:flex;"><span><span style="color:#008000;font-weight:bold">echo</span> <span style="color:#19177c">$obj</span><span style="color:#666">-></span><span style="color:#7d9029">show_detail</span>();
</span></span><span style="display:flex;"><span><span style="color:#bc7a00">?></span><span >
</span></span></span></code></code>

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Ausgabe:

<code>
<code class="language-text hljs" data-lang="text"><span style="display:flex;"><span>Alice : Your Id Number is 1036398
</span></span></code></code>

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Klassenkonstrukteur. Identity 类扩展了上述代码中的 Student 类。我们使用关键字 parent: 来调用 Student

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