Extract value from a multiline pattern using PHP and preg_match

Question

I'm trying to extract a value from a multiline pattern with PHP and preg_match. The pattern I'm searching for within the string I'm passing to preg_match($regex, $string, $the_match):

Latitude:</td>
        <td class="formCell">
        40-45-40.205 N
       </tr>

I know that if it were all on one line like so:

Latitude:</td><td class="formCell">40-45-40.205 N</tr>

Then the following would be valid and it would properly extract the value:

/Latitude:<\/td><td class="formCell">(.*?)<\/tr>/

However, since the pattern I'm looking for has multiple lines the above regex doesn't work. I'm getting the initial string I'm passing to preg_match() via file_get_contents($url) so I'm at the mercy of the remote content to some extent. Any help would be much appreciated!

Full answer: /Latitude:<\/td>[\s]*<td class="formCell">[\s]*([\s\S]*?)[\s]*<\/tr>/ — dvarney
– dvarney, Commented Jul 5, 2012 at 23:33

Mitya · Accepted Answer · 2022-12-07 13:45:41Z

6

Use [\s\S] instead of ..

/Latitude:<\/td>[\s]*<td class="formCell">([\s\S]*?)<\/tr>/

. is a wildcard but does not include whitespace - including line break - characters. [\s\S] simply says "match all space and non-space characters" (i.e. anything at all).

Note I also allowed for optional space characters after </td>.

(Sidenote: the HTML is invalid - closing a table row before closing the table cell.)

edited Dec 7, 2022 at 13:45

answered Jul 5, 2012 at 22:38

Mitya

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4 Comments

dvarney Over a year ago

Winner winner chicken dinner!! (almost) I had to add another "[\s]*" after the <td class="formCell">. Like the following: /Latitude:<\/td>[\s]*<td class="formCell">[\s]*([\s\S]*?)<\/tr>/

Mitya Over a year ago

Hmm... this should not be necessary because any space characters there would be picked up by the sub-group, which accepts space characters. It worked for me as it was.

dvarney Over a year ago

Update: I also had to add [\s]* right after where the value is being extracted. /Latitude:<\/td>[\s]*<td class="formCell">[\s]*([\s\S]*?)[\s]*<\/tr>/

dvarney Over a year ago

If I didn't add those [\s]* before and after where I'm extracting the value then the line breaks get passed in with the value being extracted. You can test it real quick over at Rubular.

Jelmer · Accepted Answer · 2012-07-05 22:38:16Z

0

There is no simple flag for this. A simple hack could be:

Latitude:(.*?)<\/td>(.*?)<td class="formCell">(.*?)<\/tr>

And then add the dotall flag to your regex (s) to allow a '.'[dot] to match newlines also. But then it could match a lot more. Is it your own code or are you ripping html from a 3rd party website? Because maybe you are using regex' when you don't have to!

answered Jul 5, 2012 at 22:38

Jelmer

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1 Comment

dvarney Over a year ago

I tried it and it didn't work. @Utkanos, for the most part, was spot on.

Chris Trahey · Accepted Answer · 2012-07-05 23:00:21Z

0

I think the trick is to "sprinkle" [\s]* anywhere the HTML formal would legally allow whitespace. You do not need special flags or anything.

Latitude:[\s]*<\/td>[\s]*<td[\s]*class="formCell">[\s]*([\s\S]*?)[\s]*<\/tr>

Keep in mind that html is VERY forgiving about whitespace. You need to evaluate your input and decide what is acceptable tolerance for you.

Another caveat is that these elements may have different attributes, or different quote styles... If you must work with that as well, you will need to use more of . and then use the "unready" flag (add u after the pattern when passing it to the preg functions); and then perhaps some fancy back-referencing once you realize that > can legally occur inside of an attribute ;-)

answered Jul 5, 2012 at 23:00

Chris Trahey

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2 Comments

dvarney Over a year ago

During my initial testing I was using \s without the square brackets and asterisk. I was using Rubular for testing and in the quick reference section they never mentioned wrapping the \s in square brackets. All the other places that searched for help never mentioned the extra characters either.

Chris Trahey Over a year ago

I suppose they aren't strictly necessary (it creates a "class" of characters, but with only one member it's perhaps overkill). The asterisk is the critical part of my suggestion, and the plentiful placement.

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