Topic: [SOLVED] Matching where something is NOT found

[lemmin]

With this string:

Code: [Select]

<?php
"<img src=\"1.jpg\" /><img src=\"2.jpg\" alt=\"2\" />"
?>

I am trying to add a string like "alt=\"1\"" to only the img tag that does NOT already have an alt property

This regex matches the src property just like I want it to:

Code: [Select]

"/(<\s*img\s*src\s*=\s*[\"|'](.+?)[\"|'])/"

But when I try to match the end tag without any other characters, it gets greedy and matches the quote from the end of the alt property:

Code: [Select]

"/(<\s*img\s*src\s*=\s*[\"|'](.+?)[\"|'])\s*\/>/"

So, is there a way to implement this regex where the .+? won't match the middle quotes?

Or, what is a good way to match the img tag that doesn't have an alt property?

I know I could do it with two statements, but it seems like it should be possible with just one.

Thanks.

[lemmin]

I guess I should have thought about this harder, I just figured it out:

Code: [Select]

"/(<\s*img\s*src\s*=\s*[\"|']([^\"]*?)[\"|'])\s*\/?>/"


[effigy]

<pre>
<?php
   $data = '<img src="1.jpg" /><img src="2.jpg" alt="2" />';
   echo(
      htmlspecialchars(
         preg_replace('%<img\s+((?:(?!alt=)[^>])*?)\s*/?>%', '<img $1 alt="1" />', $data)
      )
   );
?>
</pre>

[lemmin]

Yeah, I realized that regex would only work for the strict syntax that my input was using. This would be a more universal way of matching any img tag without an alt property:

Code: [Select]

/<\s*img(.(?!alt\s*=\s*['\"]))+?\/?>/

Thanks for the help.