PHP类的方法覆盖问题

Question

<?php
    
  class person{     public $name;
      public $age;
      public $qq;      public $color;      function __construct($name,$age,$color)
     {
          $this->name=$name;
          $this->age=$age;
          $this->color=$color;
           
     }
      
     
  
      
    }  class student extends person
{      function __construct($name,$age,$color,$qq)
    {
        $this->name=$name;
        $this->qq=$qq;
    }
    
}  $sd=new student('xuxin',22,'bld',562332);   echo $td-name;
    $p=new person('ligen',22,'red');  echo $p->name,'<br />',$p->age,'<br />',$p->color;
?>构造函数怎么不能覆盖？

Answer 1

<?php
    
  class person{     public $name;
      public $age;
      public $qq;      public $color;      function __construct($name,$age,$color)
     {
          $this->name=$name;
          $this->age=$age;
          $this->color=$color;
           
     }
      
     
  
      
    }  class student extends person
{      function __construct($name,$age,$color,$qq)
    {
        $this->name=$name;
        $this->qq=$qq;
    }
    
}  $sd=new student('xuxin',22,'bld',562332);   echo $td-name;
    $p=new person('ligen',22,'red');  echo $p->name,'<br />',$p->age,'<br />',$p->color;
?>

Answer 2

php不像java
需要显示的调用父类的构造方法parent::__construct();

Answer 3

$sd=new student('xuxin',22,'bld',562332);
echo $sd->name;------------------测试哥的签名--------------------------
哥默默的低下头,不是哥修养好,而是哥在找砖头!
--------------------------------------------------------

Answer 4

继承 extend 然后调用父类的构造方法parent:

Answer 5

class MyClass
{
public $public = 'Public1';
protected $protectde = 'Protected1';
private $private = 'Private1';
function printHello()
{
echo $this->public."\n";
echo $this->protected."\n";
echo $this->private."\n";
}
}
class MyClass2 extends MyClass
{
protected $protected = 'Protected2';
function printHello()
{
echo $this->public."\n";
echo $this->protected."\n";
echo "--------\n";
echo parent::printHello()."\n";
}
}$obj2 = new MyClass2();
echo "<pre/>";$obj2->printHello();