Решение задачки посредством ООП

<?php
header("Content-type: text/html; Charset=UTF-8");
 
$arr = $_POST["field_1"];
 
class ReverseArray {
    
    public $arr = array;
    
    public function RevArray($arr){
        $this->arr = array_reverse($arr);
    }
    
    public function ShowArray() {
        print_r($this->arr);
    }
}
    $rev = new ReverseArray();
    $rev->RevArray($arr);
    $rev->ShowArray();
 
?>

public $arr = array;

public $arr = array();

<?php
header("Content-type: text/html; Charset=UTF-8");
 
$arr = $_POST["field_1"];
$newarr = explode(",",$arr);
 
class ReverseArray {
    
    public $arr = array();
    
    public function RevArray($newarr){
        $this->arr = array_reverse($newarr);
    }
    
    public function ShowArray() {
        print_r($this->arr);
    }
}
    $rev = new ReverseArray();
    $rev->RevArray($newarr);
    $rev->ShowArray();
 
?>

public function ShowArray() {
        foreach($arr as $value) {
            echo "$value";
        }
    }

public function ShowArray() {
        foreach($this->arr as $value) {
            echo "$value";
        }
    }