PHP Basics for Designers

PHP Basics for Designers
Matthew Turland
Atlanta Web Designers Group
November 11, 2008

So what is PHP?
A programming language.
Mainly intended for web applications.
Also useful for other things.
That last part is another story for another time...

Let's jump right in...
These do the same thing.
<p>Hello world!</p>
<p> <?php echo 'Hello world!'; ?> </p>

How is that useful?
When 'Hello world!' could be anything.
<?php $title = 'Goodbye cruel world!'; ?>
...
<p> <?php echo $title; ?> </p>
Result : <p>Goodbye cruel world!</p>

Can you break that down?
<?php $title = 'Goodbye cruel world!'; ?>
opening PHP tag variable assignment operator string (quote to quote) closing PHP tag end of statement

A little shorter, maybe?
<p> <?php echo $title; ?> </p>
<p> <?= $title ?> </p>
For #2, short_open_tag must be on.

Now you see me...
The HTML here is displayed.
<?php $sidebar = true; ?>
...
<?php if ($sidebar): ?>
<ul>
...
</ul>
<?php endif; ?>

... and now you don't.
The HTML here is not displayed.
<?php $sidebar = false ; ?>
...
<?php if ($sidebar): ?>
<ul>
...
</ul>
<?php endif; ?>
Here's why

On one condition...
<?php if ($page == 'home'): ?>
<ul>
...
</ul>
<?php endif; ?>
comparison operator == for “is” != for “is not”

Playing with strings
These all result in the same output.
echo 'Hello' . ' ' . 'world!';
$greeting = 'Hello';
echo $greeting . ' ' . 'world!';
$object = 'world';
echo $greeting . ' ' . $object . '!';
concatenation operator (combines strings)

Building strings
$greeting = $greeting . ' world!';
$greeting .= ' world!';

All for one...
Your standard HTML list.
<ul>
<li>Milk</li>
<li>Eggs</li>
...
<li>Bread</li>
</ul>

... one for all.
The same list of items in PHP.
<?php $list = array( 'Milk', 'Eggs', ... , 'Bread'); ?>
...
<ul>
<?php foreach ($list as $item): ?>
<li> <?php echo $item; ?> </li>
<?php endforeach; ?>
</ul>

Adding a dimension...
<?php
$links = array(
array(
'text' => 'Exciting new headline',
'href' => '/exciting-new-headline'
),
array(
'text' => 'News from yesterday',
'href' => '/news-from-yesterday'
)
);
?>
“ row” “ column” key value

... and displaying it.
<ul>
<?php foreach ($links as $link): ?>
<li><a href=” <?php echo $link['href']; ?> ”>
<?php echo $link['text']; ?> </a></li>
<?php endforeach; ?>
</ul>

The results are in!
<ul>
<li><a href=” /exciting-new-headline ”> Exciting New Headline </a></li>
<li><a href=” /news-from-yesterday ”> News from yesterday </a></li>
</ul>

The not-so-great wall
http://example.com/foo.php?title=<script>...
<p> <?= $_GET['title'] ?> </p>
Result : <p><script>...</p>
Most likely, this is not good for security.

The great escape
http://example.com/foo.php?title=<script>...
<p> <?= htmlspecialchars($_GET['title']) ?> </p>
Result : <p><script>...</p>
Rendered result: <script>

Stylish yet functional
Functions are reusable bits of code.
function ul($items) {
$result = '<ul>';
foreach ($items as $item) {
$result .= '<li>' . htmlspecialchars($item) . '</li>';
}
return $result . '</ul>';
}

Call me
This...
<?= ul(array('Milk', 'Eggs', 'Bread')) ?>
... becomes this...
<ul><li>Milk</li><li>Eggs</li><li>Bread</li></ul>

Plug and play <?php include 'header.html'; ?> <?php include 'navigation.php'; ?> Content <?php include 'footer.html'; ?> <?php include 'sidebar.html'; ?>

Want to learn more?
http://php.net/manual/en
http://phpcommunity.org
irc://irc.freenode.net/phpc
http://phpwomen.org
irc://irc.freenode.net/phpwomen
http://phpbuilder.com/board
http://www.amazon.com/dp/0596005601

To sum it up...
Avoid copy and paste. Includes and functions!
Before outputting variables, escape them!
PHP has lots of built-in functions. Use them!
Don't let your learning about PHP stop here!

Questions?

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PHP Basics for Designers

by Matthew Turland

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