PHP object-oriented constructor description

: This article describes PHP Object-oriented constructors. For more information about PHP tutorials, see. This article will not go into detail on object-oriented knowledge. This article focuses on PHP constructor.
Php constructor can be magic cube _ construct () or a function with the same name as the class. The example is as follows:

classA{publicfunctionA(){echo'A is constructing...';    }  } classB{publicfunction__construct(){echo'B is contructing...';    } } $a = new A();   // A is constructing...$b = new B();   // B is constructing...

In addition, you should note that:
【Sub-classes can use the constructor of the parent class without writing constructor.]

classA{protected$name;    publicfunctionA(){echo'A is constructing...
';    }    publicfunctionset_name($name){$this->name = $name;    }    publicfunctionget_name(){return$this->name;    } } classBextendsA{/*    public function __construct(){        echo 'B is contructing...
';    }    */ } //$a = new A();$b = new B();  // A is constructing...$b->set_name('zhangsan'); echo$b->get_name();

【If the subclass has a constructor, the constructor of the parent class will no longer be called.]

classA{protected$name;    publicfunctionA(){echo'A is constructing...
';    }    publicfunctionset_name($name){$this->name = $name;    }    publicfunctionget_name(){return$this->name;    } } classBextendsA{publicfunction__construct(){echo'B is contructing...
';    } } //$a = new A();$b = new B(); // just echo 'B is contructing...'$b->set_name('zhangsan'); echo$b->get_name(); // zhangsan

【If the constructor of the parent class is private, it can be inherited, but the sub-class must have its own constructor and be clearly written.]

classA{protected$name;    privatefunctionA(){echo'A is constructing...
';    }    publicfunctionset_name($name){$this->name = $name;    }    publicfunctionget_name(){return$this->name;    } } classBextendsA{publicfunction__construct(){echo'B is contructing...
';    } } //$a = new A();$b = new B(); // B is contructing...$b->set_name('zhangsan'); echo$b->get_name();  // zhangsan

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