I seem to be having some trouble writing a regular expression parser for a PHP application I'm developing. I'd like to be able to parse a Wikipedia page and have an expression match each link that points to another Wikipedia page. I've written this regular expression:
Code: /<a href=\"http:\/\/en.wikipedia.org\/wiki\/(.*)\"/
but it only works on the first link per line in the html file. Any idea why this is?
magicdanw wrote:
I seem to be having some trouble writing a regular expression parser for a PHP application I'm developing. I'd like to be able to parse a Wikipedia page and have an expression match each link that points to another Wikipedia page. I've written this regular expression:
Code: /<a href=\"http:\/\/en.wikipedia.org\/wiki\/(.*)\"/
but it only works on the first link per line in the html file. Any idea why this is?/<a href=\"http:\/\/en.wikipedia.org\/wiki\/(.*)\"/ig
Hmm g doesn't seem to be a valid regex modifier in php... What were you attempting to do? I do see the goal of the i modifier (case-insensitivity), but Wikipedia seems to be consistent with it's url case.
'g' is the global flag, it means the regex will match every instance of the specified pattern rather than just the first instance. I can't remember the g flag not working for me, what's your full line of php?
Code: echo preg_replace("/<a href=\"http:\/\/en.wikipedia.org\/wiki\/(.*)\"/i", "<a href=\"index.php?date=" . $_GET["date"] . "&title=$1\"", $original);
The odd thing is, I run it once for the whole document, not once per line, yet it replaces exactly one instance of the pattern per line.
Your regular expression (.*) is greedy. Make it non-greedy (.*?) instead.
Code: echo preg_replace(
'#<a href="http://en.wikipedia.org/wiki/(.*?)"#i',
'<a href="index.php?date="' . $_GET["date"] . '&title=$1"',
$source
);
Thanks Ben, it works like a charm!
benryves wrote:
Your regular expression (.*) is greedy. Make it non-greedy (.*?) instead.
Code: echo preg_replace(
'#<a href="http://en.wikipedia.org/wiki/(.*?)"#i',
'<a href="index.php?date="' . $_GET["date"] . '&title=$1"',
$source
);
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