PHP replace text in variable

Question

$image variable gives this code (when echo is used):

<img src="/image.png" width="100" height="147" alt="" class="some_class" />

width, height, src and class attributes can be different.

What should we do:

remove width and height from $image
replace alt="" with alt="Poster"

Thanks.

Are the widht/height incorrect or why do you want to remove them? — DrColossos
– DrColossos, Commented Jul 4, 2010 at 17:43
@Happy: Doubtful, it's not proper to remove parts of HTML in PHP, only insert things into it. Why don't you find the HTML and remove the width and height attributes and set an ALT? You don't need PHP to do that for you. — animuson
– animuson ♦, Commented Jul 4, 2010 at 17:51

tomit · Accepted Answer · 2010-07-04 18:19:33Z

1

I'd use regular expressions to do this.

// Replace width="..." and height="..." with nothing
$variable = preg_replace('/(width|height)\s*=\s*"[^"]*"/i', '', $image);

// Replace alt="..." with alt="Poster"
$variable = preg_replace('/alt\s*=\s*"[^"]*"/i', 'alt="Poster"', $variable);

This method is not dependant on the order of the attributes, which of the some other answers are. Also note that the second regular expressions will replace alt="<any string here>" with alt="Poster". It should be easy enough to change it to only replace alt="" though.

edited Jul 4, 2010 at 18:19

answered Jul 4, 2010 at 18:10

tomit

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Comments

Sergey Eremin · Accepted Answer · 2010-07-04 18:11:38Z

1

$pattern = '/alt="" width="\d+" height="\d+"/i';
$replacement = 'alt="Poster"';
$variable = preg_replace($pattern, $replacement, $variable);

fix to work with any order of attributes(Gordon's comment):

$pattern = '/alt=""/i';
$replacement = 'alt="Poster"';
$variable = preg_replace($pattern, $replacement, $variable);
$pattern = '/width="\d+"/i';
$replacement = '';
$variable = preg_replace($pattern, $replacement, $variable);
$pattern = '/height="\d+"/i';
$replacement = '';
$variable = preg_replace($pattern, $replacement, $variable);

edited Jul 4, 2010 at 18:11

answered Jul 4, 2010 at 18:04

Sergey Eremin

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2 Comments

Gordon Over a year ago

this assumes the attributes will always appear in that order.

Gordon Over a year ago

what if the attributes appear with more whitespace inbetween e.g. alt = "" width= "100" height= "147"?

Gordon · Accepted Answer · 2010-07-04 18:22:19Z

1

If the attributes can be variable, then your best choice for working with the HTML is to use a library that actually understands HTML, like DOM.

$dom = new DOMDocument;
$dom->loadXML($variable);
$dom->documentElement->removeAttribute('width');
$dom->documentElement->removeAttribute('height');
$dom->documentElement->setAttribute('alt', 'poster');
echo $dom->saveXML($dom->documentElement);

outputs:

<img src="http://site.com/image.png" alt="poster"/>

edited Jul 4, 2010 at 18:22

answered Jul 4, 2010 at 17:54

Gordon

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2 Comments

Happy Over a year ago

Thanks Gordon! 1) with and height can be different. 2) replacement for alt doesn't work

DrColossos Over a year ago

I'd suggest 'width="100" height="147" alt=""' since there are going to be 2 alt's after your solution.

ZurabWeb · Accepted Answer · 2012-04-14 16:06:05Z

0

will also replace <embed width="x"> which is wrong. We need to catch only with <img> tag

answered Apr 14, 2012 at 16:06

ZurabWeb

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