Philadelphia Reflections

The musings of a physician who has served the community for over six decades

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The website technology supporting Philadelphia Reflections is PHP, MySQL and DHTML. The web hosting service is Internet Planners. The development of this website has provided an opportunity to learn new technology, to try out different techniques for getting noticed by the search engines and the trials and tribulations of dealing with malicious hackers and spammers who range from the annoying to the abusive. This collection of articles documents some of our experiences and we hope that people surfing the web looking for solutions to problems we've encountered will benefit.

George and Computers(1)
I got him into computers around 1960. He soon far surpassed me.

Parsing name-value pair attributes in an HTML tag

Not only do the attributes in an HTML tag come in random order but many are optional

Here's a regex solution:

<?php
function tagAttr($matches) {print_r($matches);}

$string = '<img src="/images/picture.jpg" width="300" class="left" alt="alt keywords" />';

$foo	= preg_replace_callback(
'/<img\b(?>\s+(?:alt="([^"]*)"|class="([^"]*)"|style="([^"]*)"|src="([^"]*)"|height="([^"]*)"|width="([^"]*)")|[^\s>]+|\s+)*>/i',
"tagAttr",
$string);
?>

Produces the following:

Array
(
    [0] => <img src="/images/picture.jpg" width="300" class="left" alt="alt keywords" />
    [1] => alt keywords
    [2] => left
    [3] => 
    [4] => /images/picture.jpg
    [5] => 
    [6] => 300
)

The regex is a series of alternating sequences; so, add href="([^"]*)"| in front of alt="([^"]*)" to select an additional attribute.

$matches[0] is the complete match
$matches[1] is alt=
$matches[2] is class=
$matches[3] is style=
$matches[4] is src=
$matches[5] is height=
$matches[6] is width=

My thanks (a) to Flagrant Badassery for putting me onto the idea and (b) to http://centricle.com/tools/html-entities/ for HTML encoding

 

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(HTML tags provide better formatting)