PHP object-oriented constructor description

This article will not go into details about object-oriented knowledge. This article focuses on the constructor of PHP.
The constructor of a php class can be the magic cube __construct() or a function with the same name as the class. Examples are as follows:

<code><span><span>class</span><span>A</span>{</span><span>public</span><span><span>function</span><span>A</span><span>()</span>{</span><span>echo</span><span>'A is constructing...'</span>;
    } 
 }
 <span><span>class</span><span>B</span>{</span><span>public</span><span><span>function</span><span>__construct</span><span>()</span>{</span><span>echo</span><span>'B is contructing...'</span>;
    }
 }

 <span>$a</span> = <span>new</span> A();   <span>// A is constructing...</span><span>$b</span> = <span>new</span> B();   <span>// B is constructing...</span></code>

In addition, when inheriting, you should pay attention to the following:
[The subclass does not need to write a constructor, then use the constructor of the parent class]

<code><span><span>class</span><span>A</span>{</span><span>protected</span><span>$name</span>;
    <span>public</span><span><span>function</span><span>A</span><span>()</span>{</span><span>echo</span><span>'A is constructing...<br>'</span>;
    }
    <span>public</span><span><span>function</span><span>set_name</span><span>(<span>$name</span>)</span>{</span><span>$this</span>->name = <span>$name</span>;
    }
    <span>public</span><span><span>function</span><span>get_name</span><span>()</span>{</span><span>return</span><span>$this</span>->name;
    }
 }
 <span><span>class</span><span>B</span><span>extends</span><span>A</span>{</span><span>/*
    public function __construct(){
        echo 'B is contructing...<br>';
    }
    */</span> }

 <span>//$a = new A();</span><span>$b</span> = <span>new</span> B();  <span>// A is constructing...</span><span>$b</span>->set_name(<span>'zhangsan'</span>);
 <span>echo</span><span>$b</span>->get_name();</code>

[If the subclass writes a constructor, the constructor of the parent class will not be called again]

<code><span><span>class</span><span>A</span>{</span><span>protected</span><span>$name</span>;
    <span>public</span><span><span>function</span><span>A</span><span>()</span>{</span><span>echo</span><span>'A is constructing...<br>'</span>;
    }
    <span>public</span><span><span>function</span><span>set_name</span><span>(<span>$name</span>)</span>{</span><span>$this</span>->name = <span>$name</span>;
    }
    <span>public</span><span><span>function</span><span>get_name</span><span>()</span>{</span><span>return</span><span>$this</span>->name;
    }
 }
 <span><span>class</span><span>B</span><span>extends</span><span>A</span>{</span><span>public</span><span><span>function</span><span>__construct</span><span>()</span>{</span><span>echo</span><span>'B is contructing...<br>'</span>;
    }

 }

 <span>//$a = new A();</span><span>$b</span> = <span>new</span> B(); <span>// just echo 'B is contructing...'</span><span>$b</span>->set_name(<span>'zhangsan'</span>);
 <span>echo</span><span>$b</span>->get_name(); <span>// zhangsan</span></code>

[ If the constructor of the parent class is private, it can be inherited, but the subclass must have its own constructor and write it clearly]

<code><span><span>class</span><span>A</span>{</span><span>protected</span><span>$name</span>;
    <span>private</span><span><span>function</span><span>A</span><span>()</span>{</span><span>echo</span><span>'A is constructing...<br>'</span>;
    }
    <span>public</span><span><span>function</span><span>set_name</span><span>(<span>$name</span>)</span>{</span><span>$this</span>->name = <span>$name</span>;
    }
    <span>public</span><span><span>function</span><span>get_name</span><span>()</span>{</span><span>return</span><span>$this</span>->name;
    }
 }
 <span><span>class</span><span>B</span><span>extends</span><span>A</span>{</span><span>public</span><span><span>function</span><span>__construct</span><span>()</span>{</span><span>echo</span><span>'B is contructing...<br>'</span>;
    }

 }

 <span>//$a = new A();</span><span>$b</span> = <span>new</span> B(); <span>// B is contructing...</span><span>$b</span>->set_name(<span>'zhangsan'</span>);
 <span>echo</span><span>$b</span>->get_name();  <span>// zhangsan</span></code>

Copyright statement: This article is an original article by the blogger without the permission of the blogger. No reproduction allowed.

The above introduces the description of PHP object-oriented constructor, including the relevant content. I hope it will be helpful to friends who are interested in PHP tutorials.