August 2012
Beginner
583 pages
16h 1m
English
Content preview from Learning PHP, MySQL, JavaScript, and CSS, 2nd Edition
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An Example Program
Let’s 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.
Example 11-10. A program to convert values between Fahrenheit and
Celsius
<?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.
Figure 11-8. The temperature conversion program in action
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 two lines ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.