Regex code exception gif [closed] - regex

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I have the following function that returns me the first image of the post:
$output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i',
$post->post_content, $matches);
however returns me any image, I need to ignore the images in gif format, how could I add this condition in regex expression?

Answer 1

Easier to loop through the results and use a different regex.
$output = preg_match_all('/<img[^>]+?src=[\'"](.+?)[\'"].*?>/i', $post->post_content, $matches);
foreach ($matches as $imgSrc)
{
if (!preg_match("/\.gif$/i"), $imgSrc)
{
$noGif[] = $imgSrc;
}
}
It is easier to understand, and there won't be unexpected side effects like blocking valid pictures that happen to have the letter "gif" in the file name.
Note, be very carefull when using .+ and .*. As it stands, your regex matches a LOT more than you think:
Try it on this, for instance:
<img whatever> whatever <img src="mypic.png"> <some other tag>

Answer 2

You should probably not be using regular expressions
HTML is not regular
Regexes may match today, but what about tomorrow?
Say you've got a file of HTML where you're trying to extract URLs from tags.
<img src="http://example.com/whatever.jpg">
So you write a regex like this (in Perl):
if ( $html =~ /<img src="(.+)"/ ) {
$url = $1;
}
In this case, $url will indeed contain http://example.com/whatever.jpg. But what happens when you start getting HTML like this:
<img src='http://example.com/whatever.jpg'>
or
<img src=http://example.com/whatever.jpg>
or
<img border=0 src="http://example.com/whatever.jpg">
or
<img
src="http://example.com/whatever.jpg">
or you start getting false positives from
<!-- <img src="http://example.com/outdated.png"> -->

Answer 3

<img[^>]+src=[\'"](?:([^\'"](?!\.gif))+)[\'"][^>]*>
Updated to have only one capture.
Fixed to include dot. Now would only fail on strange things like a.gif.jpg
Also added safety matches as suggested in comment.