PHP Help with regular expressions... error: Delimiter must not be alphanumeric.

Question

I am new to regexp in php. I am just trying to do a simple preg_match on two strings. Here is my code:

$pattern = '\\w*'.strtolower($CK);

if(preg_match($pattern, $rowName, $matches) == true)
            {
                echo 'true';

            }

But I keep getting the error:

Warning: preg_match() [function.preg-match]: Delimiter must not be alphanumeric or backslash in /home/daskon/public_html/reflexInvestor_dev/php/rss_functions.php on line 319

I imagine it's because I need to put something after the pattern, but I can;t seme to find what that is. When I try the same pattern in a regexp tester, it works fine.

Answer 1

You need to wrap the pattern in a delimiter that marks the beginning and end. Any "non-alphanumeric, non-backslash, non-whitespace" character works. / is very common, so:

$pattern = '/\\w*' . strtolower($CK) . '/';

The reason for the delimiter is you can include pattern modifiers in the pattern, but they appear after the delimiter

Answer 2

You need to wrap the pattern in delimiting characters (I like to use # since I rarely need them inside of the regex):

if (preg_match('#' . $pattern . '#', $rowName, $matches)) {

(You also don't need the == true, it's redundant since that's what the if does anyway internally...)