The difference between public, protected and private

Draw conclusions through className::functionNmae(), instantiation, parent, self

className::functionNmae() needs to be a static method (public mode)

parent::functionNmae() The parent class needs to be static Methods (two modes, public and protected)

self::functionNmae() This class must be a static method (three modes)

Instantiation: After instantiation, you can access static methods or ordinary methods in public mode

1. Direct access (through className::functionNmae() and instantiation):

Conclusion:

                                                          ‐                           using using using using using using ’s out of ’s ’s to be accessible through className::functionNmae()-- ) Access                                                                                                                                                     
private
                                                                                                 | >functionName() access

<?<span>php
</span><span>/*</span><span>*
 * 
 * @authors HG (hg0728@qq.com)
 * @date    2015-05-26 17:12:02
 * @version 1.0
 </span><span>*/</span><span>header</span>("Content-type:text/html;charset=utf-8"<span>);
</span><span>class</span><span> A {
    </span><span>static</span><span>$name</span>='这是类A的静态变量'<span>;

    </span><span>static</span><span>public</span><span>function</span><span> stc_pc(){
        </span><span>echo</span> '这是类A的公共静态方法<br />'<span>;
    }
    </span><span>static</span><span>function</span><span> stc(){
        </span><span>echo</span> '这是类A的静态方法<br />'<span>;
    }
    </span><span>static</span><span>protected</span><span>function</span><span> stc_pd(){
        </span><span>echo</span> '这是类A受保护的静态方法<br />'<span>;
    }
    </span><span>static</span><span>private</span><span>function</span><span> stc_pe(){
        </span><span>echo</span> '这是类A私有的静态方法<br />'<span>;
    }
}


A</span>::stc_pc();<span>//</span><span>可访问</span><span>A</span>::stc();<span>//</span><span>可访问</span><span>A</span>::<span>$name</span>;<span>//</span><span>不报错

//A::stc_pd();//不可访问

//A::stc_pe();//不可访问</span><span>echo</span> '<br><br>通过实例化访问<br><br>'<span>;


</span><span>$a</span> = <span>new</span><span> A();

</span><span>$a</span>->stc_pc();<span>//</span><span>可访问</span><span>$a</span>->stc();<span>//</span><span>可访问

//$a->$name;//报错

//$a->stc_pd();//不可访问

//$a->stc_pe();//不可访问</span><span>/*</span><span>*******************
          | 可以 通过 className::functionNmae() 访问
public    | 
          | 可以 通过实例 $obj->functionName() 访问        

          | 不可 通过 className::functionNmae() 访问
protected | 
          | 不可 通过实例 $obj->functionName() 访问    

          | 不可 通过 className::functionNmae() 访问
private   | 
          | 不可 通过实例 $obj->functionName() 访问    
*******************</span><span>*/</span>

2. Direct access (self::functionNmae())

Conclusion:

self::functionNmae(); needs to be a static method (all three modes are available)

<?<span>php
</span><span>/*</span><span>*
 * 
 * @authors HG (hg0728@qq.com)
 * @date    2015-05-26 17:18:50
 * @version 1.0
 </span><span>*/</span><span>header</span>("Content-type:text/html;charset=utf-8"<span>);

</span><span>class</span><span> C {
    </span><span>static</span><span>$name</span> = "静态变量"<span>;  
    </span><span>static</span><span>public</span><span>function</span><span> stc_pc(){        
        </span><span>echo</span> '静态公共方法<br>'<span>;
        self</span>::<span>stc_pd();
        self</span>::<span>stc_pe();
        self</span>::<span>stc();
        </span><span>//</span><span>self::func();//报错但有结果</span><span>
    }

    </span><span>static</span><span>protected</span><span>function</span><span> stc_pd(){
        </span><span>echo</span> '静态受保护方法<br>'<span>;
    }
    </span><span>static</span><span>private</span><span>function</span><span> stc_pe(){        
        </span><span>echo</span> '静态受保护方法<br>'<span>;
    }

    </span><span>static</span><span>function</span><span> stc(){        
        </span><span>echo</span> '静态普通方法<br>'<span>;
    }
    </span><span>function</span><span> func(){        
        </span><span>echo</span> '普通方法<br>'<span>;
    }
    
}


C</span>::<span>stc_pc();


</span><span>/*</span><span>*****

self::functionNmae();需是静态方法(三种模式都可)

*****</span><span>*/</span>

3. Access the parent class through subclasses (parent::functionNmae() and instantiation)

Conclusion:

parent::functionNmae(); private is not accessible

$obj->functionNmae(); private is not accessible

<?<span>php
</span><span>/*</span><span>*
 * 
 * @authors HG (hg0728@qq.com)
 * @date    2015-05-26 17:18:50
 * @version 1.0
 </span><span>*/</span><span>header</span>("Content-type:text/html;charset=utf-8"<span>);
</span><span>include</span> '/class_a.php'<span>;

</span><span>class</span> B <span>extends</span><span> A{
    
    </span><span>static</span><span>public</span><span>function</span><span> index(){        
        parent</span>::<span>stc_pc();
        parent</span>::<span>stc();
        parent</span>::<span>stc_pd();
        parent</span>::<span>$name</span>;<span>//</span><span>不报错
        //parent::stc_pe();//不可访问</span><span>echo</span> '<br><br>通过实例化访问<br><br>'<span>;

        </span><span>$a</span> = <span>new</span><span> A();
        </span><span>$a</span>-><span>stc_pc();
        </span><span>$a</span>-><span>stc();
        </span><span>$a</span>-><span>stc_pd();
        </span><span>$a</span>-><span>$name</span>;<span>//</span><span>报错
        //$a->stc_pe();//不可</span><span>    }
    
}


B</span>::<span>index();

</span><span>/*</span><span>*****

在子类中通过:
parent::functionNmae(); private不可访问
$obj->functionNmae(); private不可访问

*****</span><span>*/</span>

The above has introduced the differences between public, protected, and private, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.