Why does this preg_match fail?

benton · 12-21-2009, 01:08 PM

Can someone plase explain why this statement fails?

PHP Code:


			
preg_match('/<h1>(*)<\/h1>/i', $line, $matches);

The failure results in the warning

Quote:

Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 5

If I enter this line instead (just to test the code), it works.

PHP Code:


			
preg_match('/<b class="main">(.*)<\/b>/i', $line, $matches);

girvine · 12-21-2009, 04:37 PM

Looks like your missing a dot.

In the first statement,
(*)
should be,
(.*)

benton · 12-21-2009, 06:08 PM

Thanks. Unfortunately, that was just a typo made while editing the post. The original code already had it in there. I did find that using quotes instead of apostrophes made a difference though. So this now works:

PHP Code:


			
preg_match("/<td align=\"right\" valign=\"top\"><h1>(.*)<\/h1><\/td>/i", $line, $matches);

I had to add more code in the check to get it to work.

So the next step is to read that in from the database so it works without manual edits. This is what I am trying to do (the top line is simulating what would be read from the database):

PHP Code:


			
$search_str = '<td align="right" valign="top"><h1>(.*)</h1></td>';

$search_str = str_replace("/", "\\/", $search_str);

$search_str = str_replace('"', '\\"', $search_str);

$condition = '"/'.$search_str . '/i"';



preg_match($condition, $line, $matches);

That doesn't create any erros and when I look at the source, the $condition appears exactly as when I type it in directly but the match isn't found. Does anyone have any suggestions on what might make this fail?

girvine · 12-21-2009, 07:16 PM

If I take out the quotes around the condition and don't escape the quotes inside the condition,

PHP Code:


			
$search_str = '<td align="right" valign="top"><h1>(.*)</h1></td>'; 

$search_str = str_replace("/", "\\/", $search_str); 

$condition = '/'.$search_str . '/i'; 



preg_match($condition, $line, $matches);

it seems to work.

benton · 12-21-2009, 11:57 PM

That did it. Thanks for taking the time to help. It is much appreciated. :)