Question

I’ve been trying to use grubers latest url matching regex in a php project.

To test it I threw together something very simple:

$regex = "(?i)\b((?:[a-z][\w-]+:(?:/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:"'.,<>?«»“”‘’]))";

$array = pret_match_all($regex, $theblockofurltext);

print_r($array);

The first problem was the ” would escape a string, depending which I wrapped the regex with, so I just removed it. The use of this is personal and I will never have ” anywhere near a url anyway. This left me with a new regex.

$regex = "(?i)\b((?:[a-z][\w-]+:(?:/{1,3}|[a-z0-9%])|www\d{0,3}[.]|[a-z0-9.\-]+[.][a-z]{2,4}/)(?:[^\s()<>]+|\(([^\s()<>]+|(\([^\s()<>]+\)))*\))+(?:\(([^\s()<>]+|(\([^\s()<>]+\)))*\)|[^\s`!()\[\]{};:'.,<>?«»“”‘’]))";

Raring to go I then ran my little script and it gave me the following error:

Warning: preg_split() [function.preg-split]: Unknown modifier '\' in D:\wwwroot\xxx\index.php on line 14

Unfortunately my REGEX class at school wasn’t taught to anywhere near the levels of this regex requires, and I have no idea where to begin fixing this for use with PHP. Any help would be greatly appreciated. No doubt I’m probably doing something stupid too, so please go easy on me 🙂

Jon

Answer 1

If you use PCRE, the regular expression must be enclosed in delimiters. Now, parenthesis () can also be delimiters, that is why the engine thinks, your expression is only (?i) and interprets the next \ as modifier.

You could use ~ as delimiter:

$regex = "~(?i)\b...]))~";

Update:

I don’t know whether PHP supports the partial modifying of an expression with (?i). So you might have to remove this and put the modifier after the delimiter instead (you apply it to the whole expression anyway):

$regex = "~\b...]))~i";