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

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...

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>

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>

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

<?php $title = 'Goodbye cruel world!'; ?>

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

These do the same thing.

<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; ?>

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

The HTML here is not displayed.

<?php $sidebar = false ; ?>

...

<?php if ($sidebar): ?>

<ul>

...

</ul>

<?php endif; ?>

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

<?php if ($page == 'home'): ?>

<ul>

...

</ul>

<?php endif; ?>

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)

These all result in the same output.

echo 'Hello' . ' ' . 'world!';

$greeting = 'Hello';

echo $greeting . ' ' . 'world!';

$object = 'world';

echo $greeting . ' ' . $object . '!';

Building strings These do the same thing. $greeting = 'Hello'; $greeting = $greeting . ' world!'; $greeting = 'Hello'; $greeting .= ' world!';

These do the same thing.

$greeting = 'Hello';

$greeting = $greeting . ' world!';

$greeting = 'Hello';

$greeting .= ' world!';

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

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>

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

<?php

$links = array(

array(

'text' => 'Exciting new headline',

'href' => '/exciting-new-headline'

),

array(

'text' => 'News from yesterday',

'href' => '/news-from-yesterday'

)

);

?>

... 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>

<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>

<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.

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>&lt;script&gt;...</p> Rendered result: <script>

http://example.com/foo.php?title=<script>...

<p> <?= htmlspecialchars($_GET['title']) ?> </p>

Result : <p>&lt;script&gt;...</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>'; }

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>

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

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!

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?