Question

I am using this regular expression to filter .pdffiles from the webpage:

    $regex='|<a.*?href="(.*pdf?)"|';

It does the job if the link is like this:

 www.xyz.com/trgrrtr/ghtty.pdf

but if the links are something like this, it is unable to filter:

 www.xyz.com/trgrrtr/ghtty.pdf?code=KksRHhdVXAoECBFCVFpeXBsBUgYMDQpxd3J2d3F2fDtzfnFuLiErNXNpIG5kYm16aGhpcmxoa05QV1VKUVFFUxQ%3D

What regular expression I should use to filter out this link from a webpage?

Answer 1

First of all, you need to escape the ? otherwise it just makes the f in front of it optional. Then you could do something like this:

$regex = '|<a.*?href="([^"]*\.pdf\?[^"]*)"|';

The use of the negated character class makes sure that you cannot leave the attribute. (.* could consume the attribute-ending " as well, and go on until " matches another double quote further down the string.)

But I really recommend that you use a DOM parser to find the link-elements first. PHP has a built-in one and there is a very nice and convenient 3rd-party alternative.