tabindex

Этот атрибут определяет порядок перехода клавишей "Tab".

index.php

<?php
class Electro {
private $show0;
private $show1;
private $price;
function __construct($arg0, $arg1, $arg2) {
$this->show0 = $arg0;
$this->show1 = $arg1;
$this->price = $arg2;
}
function Res() {
return $this->show1 - $this->show0;
}
function Sum() {
return round( $this->price * $this->Res(), 2);
}
}
?>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Name Page</title>
</head>
<body>
<?php
if($_SERVER['REQUEST_METHOD'] == 'POST') {
$show0 = abs((int)$_POST['show0']);
$show1 = abs((int)$_POST['show1']);
$price = (float)$_POST['price'];
$E = new Electro($show0, $show1, $price);
if($_REQUEST['clear']) {
$show0 = null;
$show1 = null;
$price = null;
}
}
?>
<form id="form1" action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
<fieldset>
<legend>To calculate electricity</legend>
<br />
<input tabindex="1" autofocus="autofocus" type="text" name="show0" value="<?php echo $show0; ?>" />
  
<label>The start data</label>
<br />
<br />
<input tabindex="2" type="text" name="show1" value="<?php echo $show1; ?>" />
  
<label>The end data</label>
<br />
<br />
<input tabindex="3" type="text" name="price" value="<?php echo $price; ?>" />
  
<label>The price 1 kW/hour of electricity</label>
<br />
<br />
<input tabindex="4" type="submit" name="res" value="Calculate" />
<br />
<br />
<input type="submit" name="clear" value="    Clear    " />
<br />
<br />
</fieldset>
<br />
<fieldset>
<legend>The sum of electricity</legend>
<br />
<?php
if($_SERVER['REQUEST_METHOD']=='POST' && $_REQUEST['res'] && !$_REQUEST['clear']) {
echo 'Sum = ', '<b>', $E->Sum(), '</b>';
}
else {
echo null;
}
?>
<br />
<br />
</fieldset>
</form>
</body>
</html>

<?php
class Electro {
private $show0;
private $show1;
private $price;
function __construct($arg0, $arg1, $arg2) {
$this->show0 = $arg0;
$this->show1 = $arg1;
$this->price = $arg2;
}
function Res() {
return $this->show1 - $this->show0;
}
function Sum() {
return round( $this->price * $this->Res(), 2);
}
}
?>
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<title>Name Page</title>
</head>
<body>
<?php
if($_SERVER['REQUEST_METHOD'] == 'POST') {
$show0 = abs((int)$_POST['show0']);
$show1 = abs((int)$_POST['show1']);
$price = (float)$_POST['price'];
$E = new Electro($show0, $show1, $price);
if($_REQUEST['clear']) {
$show0 = null;
$show1 = null;
$price = null;
}
}
?>
<form id="form1" action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
<fieldset>
<legend>To calculate electricity</legend>
<br />
<input tabindex="1" autofocus="autofocus" type="text" name="show0" value="<?php echo $show0; ?>" />
  
<label>The start data</label>
<br />
<br />
<input tabindex="2" type="text" name="show1" value="<?php echo $show1; ?>" />
  
<label>The end data</label>
<br />
<br />
<input tabindex="3" type="text" name="price" value="<?php echo $price; ?>" />
  
<label>The price 1 kW/hour of electricity</label>
<br />
<br />
<input tabindex="4" type="submit" name="res" value="Calculate" />
<br />
<br />
<input type="submit" name="clear" value="    Clear    " />
<br />
<br />
</fieldset>
<br />
<fieldset>
<legend>The sum of electricity</legend>
<br />
<?php
if($_SERVER['REQUEST_METHOD']=='POST' && $_REQUEST['res'] && !$_REQUEST['clear']) {
echo 'Sum = ', '<b>', $E->Sum(), '</b>';
}
else {
echo null;
}
?>
<br />
<br />
</fieldset>
</form>
</body>
</html>