<?php require_once './calculator.php'; $obj = new calculator(); echo '<pre>'; print_r($_POST); $first = $_POST['first-number']; $second = $_POST['second-number']; $button = $_POST['btn']; if ($button == 'add') { $add = $obj->add($first, $second); } if ($button == 'sub') { $add = $obj->sub($first, $second); } if ($button == 'mul') { $add = $obj->mul($first, $second); } if ($button == 'div') { $add = $obj->div($first, $second); } if ($button == 'mod') { $add = $obj->mod($first, $second); } ?> <html> <head> <title>Calculator</title> </head>