write this on the writing side
For first 100 units – Rs. 4
For next 100 units – Rs. 5
For next all units – Rs. 6
<!DOCTYPE html>
<head>
<title>Calculate Electricity Bill</title>
</head>
<?php
$result_str = $result = '';
if (isset($_POST['unit-submit'])) {
$units = $_POST['units'];
if (!empty($units)) {
$result = calculate_bill($units);
$result_str = 'Total amount of ' . $units . ' - '
. $result;
}
}
function calculate_bill($units) {
$unit_cost_first = 4;
$unit_cost_second = 5;
$unit_cost_third = 6;
if($units <= 100) {
$bill = $units * $unit_cost_first;
}
else if($units > 100 && $units <= 200) {
$temp = 100 * $unit_cost_first;
$remaining_units = $units - 100;
$bill = $temp + ($remaining_units *
$unit_cost_second);
}
else {
$temp = (100 * 4) + (100 * $unit_cost_second);
$remaining_units = $units - 200;
$bill = $temp + ($remaining_units *
$unit_cost_third) ;
}
return number_format((float)$bill, 2, '.', '');
}
?>
<body>
<div id="page-wrap">
<h1>Php - Calculate Electricity Bill</h1>
<form action="" method="post" id="quiz-form">
<input type="number" name="units"
id="units" placeholder="Please enter no. of Units" />
<input type="submit" name="unit-submit"
id="unit-submit" value="Submit" />
</form>
<div>
<?php echo '<br />' . $result_str; ?>
</div>
</div>
</body>
</html>