PHP Example
Screen shot
To enter number and change the background color.
<?php
if (isset($_POST[\'btn\']))
{
$col=$_POST[\'t1\'];
switch($col)
{
case 1:
$p=\'#ff0000\';
break;
case 2:
$p=\'pink\';
break;
case 3:
$p=\'#ffcc66\';
break;
case 4:
$p=\'pink\';
break;
case 5:
$p=\'#ffffff\';
break;

default:
$p=\'#99ffcc\';
}
}
?>
<html>
<head>
<title>back color</title>
</head>
<body bgcolor=\"<?php  if(isset($p)) echo $p; ?>\">
<form name=\"\"  method=\"post\" >
Enter number to change bgcolor
<input type=\"text\" name=\"t1\">
<br>
<input type=\"submit\" name=\"btn\" value=\"Submit\">
</form>
</body>
</html>

\"img4\"

You can download source code here