PHP

Increment/decrement Operators

Operator	Description	Example	Result
++	Pre-Increment	++$a	Increments $a by one, then returns $a.
++	Post-Increment	$a++	Returns $a, then increments $a by one.
--	Pre-Decrement	--$a	Decrements $a by one, then returns $a.
--	Post-Decrement	$a--	Returns $a, then decrements $a by one.

<html>
<head>
<title>PHP</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
echo "<h3>Pre-Increment";
$a = 15;
echo "a = ", $a,"<br />";
echo "Pre-Increment ++a: ", ++$a, "<br />";
echo "The value of a is: ", $a, "<br />";

echo "<h3>Post-Increment</h3>";
$a = 15;
echo "a = ", $a,"
";
echo "Post-Increment a++: ", $a++, "<br />";
echo "The value of a is: ", $a, "<br />";

echo "<h3>Pre-Decrement</h3>";
$a = 15;
echo "a = ", $a,"
";
echo "Pre-Decrement --a: ", --$a, "<br />";
echo "The value of a is: ", $a, "<br />";

echo "<h3>Post-Decrement</h3>";
$a = 15;
echo "a = ", $a,"
";
echo "Post-Decrement a--: ", $a--, "<br />";
echo "The value of a is: ", $a, "<br />";
?>
</p>
</body>
</html>

View the effect

Here is an example.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="EN" lang="EN">
<head>
<title>Arithmetic Operators</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<h2>Auto Parts</h2>
<b>Your order is as follows:</b>
<p>

<?php
$tireqty = 2;
$oilqty = 3;
$sparkqty = 3;
define('TIREPRICE', 50);
define('OILPRICE', 10);
define('SPARKPRICE', 4);
define('SALESTAX', 8.25);

$totalqty = $tireqty + $oilqty + $sparkqty;

$total = $tireqty * TIREPRICE + $oilqty * OILPRICE + $sparkqty * SPARKPRICE;

echo "$tireqty tires<br />";
echo "$oilqty bottles of oil<br />";
echo "$sparkqty spark plugs<br />";
echo "Items ordered: $totalqty<br />";
echo "Subtotal: \$$total<br />";

$saletax = SALESTAX/100; // Divide the sales tax by 100
$tax = $total * $saletax; // Calculate the sales tax
$saletax++; // Add 1 to the sales tax
$total = $total * $saletax; // Calculate the total
echo "Tax: \$$tax<br />";
echo "Total: \$$total";
?>

</p>
</body>
</html>

View the effect