Array as a class property, cannot assign a value?

Suppose there are classes

  
   arr = array();    }    public function getArr() {        return $this->arr;    }    public function append($arr) {        $this->arr[] = $arr;    }    public function merge($arr) {        $this->arr = array_merge($this->arr, $arr);    }}

2 function calls have different effects

  
   append($arr);//使用append无法修改类属性var_dump($obj->getArr());//output : //array(0){}$obj->merge($arr);//使用merge可以var_dump($obj->getArr());//output://array(2){'a','b'}

Why is this?

Reply content:

Suppose there are classes

  
   arr = array();    }    public function getArr() {        return $this->arr;    }    public function append($arr) {        $this->arr[] = $arr;    }    public function merge($arr) {        $this->arr = array_merge($this->arr, $arr);    }}

2 function calls have different effects

  
   append($arr);//使用append无法修改类属性var_dump($obj->getArr());//output : //array(0){}$obj->merge($arr);//使用merge可以var_dump($obj->getArr());//output://array(2){'a','b'}

Why is this?

Http://3v4l.org/Di7gT

Everything seems normal.

