在类中爆炸$ _POST输入？

I'm trying to manually reverse an array in PHP. The array is entered through a form, exploded and then reversed. I can get the code working without classes, but I am currently being taught about classes, so I'm trying to make my current code work with classes too.

<?php 
class reverseArray{

public function setSting(){
        $string = $_POST['numberInput'];
        return $string;

    }

public function explodeString(){
    $array = explode(' ', $string);
    return $array;
}

public function setArray(){
    $arrayToEcho = explodeString();
    return  $arrayToEcho;
}   


public function returnArray(){
    for ($i = count($arrayToEcho) - 1; $i >=0 ; $i--){
        echo  " ";
        $arrayToEcho[$i] = $arrayToEcho[$i];
        echo $arrayToEcho[$i];
    }
}
}
?>

I'm still very unsure if PHP classes and how to call on returns etc, so if someone could point me in the right direction? I currently get no errors or warnings, but also no output!

Looking up variable scopes will help you. You need a class property in order to use it in other methods, or functions. Right now, $string is only available inside the function it is defined at. You can declare a class property and use the $this accessor.

class reverseArray{

    public $string;

    public function setString(){
        $this->string = $_POST['numberInput'];
        return $this->string;
    }

    public function explodeString(){
        $array = explode(' ', $this->string);
        return $array;
    }

}

I think a better usage for this class would be

    public function setString($str){
        $this->string = $str;
    }

This would allow this class to be re-used as you can use any string inside the class, not just $_POST['numberInput']