square.php

<?php
class Square {
  private $height;
  private $width;

  public function setHeight($height) {
    $this->height = $height;
    $this->widh = $height;
  }

  public function getHeight() {
    return $this->height;
  }

  public function setWidth($width) {
    $this->height = $width;
    $this->widh = $width;
  }

  public function getWidth() {
    return $this->width;
  }
}

$square = new Square();
$square->setHeight(100);
$square->setWidth(80);
echo $square->getHeight(); // 80