PHP之构造析构

在实例化一个新对象时，构造方法和析构方法都会被自动调用，若有继承则会使用父类的对应方法。

• 析构方法在三种情况下会被调用：

  • 使用unset（）销毁一个对象，若存在对象传值则不会被调用；
  • 改变变量指向对象的值；
  • php程序代码运行结束后。

<code><span><span><?php </span><span><span>class</span><span>base</span>{</span><span>public</span><span>$name</span>;

    <span><span>function</span><span>__construct</span><span>(<span>$name</span>)</span>{</span><span>$this</span>->name = <span>$name</span>;
        <span>echo</span><span>'obj '</span>.<span>$this</span>->name.<span>' have built'</span>.<span>''</span>.<span>''</span>;
    }
    <span><span>function</span><span>__destruct</span><span>()</span>{</span><span>echo</span><span>'obj '</span>.<span>$this</span>->name.<span>' have destroyed'</span>.<span>''</span>.<span>''</span>;
    }
}

<span>$a</span> = <span>new</span> base(<span>'a'</span>);
<span>$b</span> = <span>new</span> base(<span>'b'</span>);
<span>$c</span> = <span>new</span> base(<span>'c'</span>);

<span>unset</span>(<span>$b</span>);
<span>$c</span> = <span>'d'</span>;</span></span></code>

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以上就介绍了PHP之构造析构，包括了方面的内容，希望对PHP教程有兴趣的朋友有所帮助。