Inheritance and usage example analysis of classes in PHP, php example analysis_PHP tutorial

Example analysis of inheritance and usage of classes in PHP, php example analysis

The examples in this article describe the inheritance and usage of classes in PHP. Share it with everyone for your reference, the details are as follows:

1. Inherit keyword: extends

Inheritance of PHP classes can be understood as sharing the content of the inherited class. Please avoid using the extends single inheritance method in PHP! (Non-C multiple inheritance) The inherited class is called the parent class (base class) and the inheritor becomes the subclass (derived class).

2. PHP inheritance rules

CLASS1------>CLASS2------>CLASS3

Inherited in turn, class3 has all the functions and attributes of class1 and class2, avoiding duplicate names of methods and attributes.

class Son｛｝ inherits class root｛｝；

class Son extends Root{};

3. Base class method overloading and parent class method access

Due to the principle of downward inheritance, the base class cannot use the content in the derived class. At this time, some methods of the base class cannot complete the functions of some of our derived classes. We can avoid method overloading and create new methods with Come the chaos.

Method overloading We can also understand method overriding, which is to perform overloading in a derived class using a method name that has the same name as a base class method.

When overloading, we need to call the original base class content and add new content. We can use

Base class name:: Method name.

Example:

<&#63;php
class Root{
  function dayin(){
    return "Root print <br />";
  }
}
 class Son extends Root{
  function dayin(){
    //return $this->dayin()."Son print <br/>";
    return Root::dayin()."Son print <br />";
  }
}
$s=new Son();
echo $s->dayin();
&#63;>

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I hope this article will be helpful to everyone in PHP programming.

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