CODEWITHSUNDEEP
phpregexpreg-match
Tom M.
Tom M.

Reputation: 149

php preg_match positive lookahead not working as expected

$regex  = '/(?<=(total: ))(\$\d+\.\d+)/';
$search = '$1.25 cart total: $24.99 $55.50';

preg_match($regex, $search, $price);

I would like to extract '$24.99' from the string above.

When I print_r the $price array, it is blank. According to this tool: http://regexr.com?2vfm9 my regex should be working correctly. When I run the code using only the "(\$\d+.\d+)" part of regex, the array returns all of the prices... so I know that part is working.

Am I implementing the positive lookahead incorrectly? Any other thoughts?

UPDATE: I think I might have found the problem:

The text that I am parsing has a "& nbsp;" after the colon. It wasn't showing when I displayed the raw text to myself, but was interfering with the regex. I'll update to confirm.

Upvotes: 1

Views: 2003

Answers (3)

Toto
Toto

Reputation: 91488

To deal with &nbsp; you could use:

$regex  = '/(?<=(total:))[^$]+(\$\d+\.\d+)/';
$search = '$1.25 cart total:&nbsp;$24.99 $55.50';

preg_match($regex, $search, $price);
print_r($price);

output:

Array
(
    [0] => &nbsp;$24.99
    [1] => total:
    [2] => $24.99
)

Upvotes: 0

Arkh
Arkh

Reputation: 8459

The problem is that your \ are not escaped:

$regex  = '/(?<=(total: ))(\\$\\d+\\.\\d+)/';

Upvotes: 0

fge
fge

Reputation: 121790

You do not need capturing parentheses around total:, in fact they are even detrimental in this case. They capture.

Try without them.

And by the way, what you are using here is a positive lookbehind, not lookahead, and I don't see why you use one at all?

Upvotes: 0

Related Questions