regular expressions conditional patterns

Hi,
I want to replace in a string all instances of width="xxx" by width="400" but only if xxx > 400.
My first approach with no condition is using:
preg_replace('/width="(\d+?)"/i', 'width="400"', $string);

Is it possible to use a conditional pattern in that case? And how?

 

In my opinion it isn't possible.

 

preg_replace('/width="(4[0-9]+[0-9]+)"/i', 'width="400"', $string);

PHP:

Replace every thing starting with 4XX should do it.

Peace,

 

#width="[4-9]\d{2,}"#i

Code (markup):

 

Is it possible to use a regular expression with a conditional pattern to replace any number greater than 400 in the second term of the preg_replace?
I tried this:
preg_replace('/width="(.*?)"/i', '/(?(\\1 > 400) width="400")/', $string);
but it did not work.
Any idea?

 

You're making it alot more complicated than it needs to be.

Check out preg_replace_callback, you can specify a function to handle replacement with it.

 

Thanks a lot, Joebert !

Here is the final working code, if anyone is interested:

function limitWidth($matches) {
if ($matches[1] > 400) return 'width="400"';
return $matches[0];
}
$string = preg_replace_callback('/width="(\d+?)"/i', 'limitWidth', string);