An Example Program
Letâs look at how a real-life PHP program integrates with an HTML form by creating the program convert.php, listed in Example 11-10. Type it in as shown and try it for yourself.
<?php // convert.php $f = $c = ""; if (isset($_POST['f'])) $f = sanitizeString($_POST['f']); if (isset($_POST['c'])) $c = sanitizeString($_POST['c']); if ($f != '') { $c = intval((5 / 9) * ($f - 32)); $out = "$f °f equals $c °c"; } elseif($c != '') { $f = intval((9 / 5) * $c + 32); $out = "$c °c equals $f °f"; } else $out = ""; echo <<<_END <html><head><title>Temperature Converter</title> </head><body><pre> Enter either Fahrenheit or Celsius and click on Convert <b>$out</b> <form method="post" action="convert.php"> Fahrenheit <input type="text" name="f" size="7" /> Celsius <input type="text" name="c" size="7" /> <input type="submit" value="Convert" /> </form></pre></body></html> _END; function sanitizeString($var) { $var = stripslashes($var); $var = htmlentities($var); $var = strip_tags($var); return $var; } ?>
When you call up convert.php in a browser, the result should look something like the screen grab in Figure 11-8.
To break the program down, the first line initializes the variables
$c
and $f
in case they do not get posted to the program. The next ...
Get Learning PHP, MySQL, JavaScript, and CSS, 2nd Edition now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.