asked on

regular expression to match all occurrences in a string

Hello Experts..
I have a requirement where I read a file in to a variable (in PHP, using file_get_contents function).
This file contains multiple tags like
<h3 attr="e"><target act="filename"></target></h3> and other tags (is not strict xml)

I need a regular expression (in PHP) that matches the above tag and returns "filename".. or the array of tags (like above) using regular expression.

I tried using preg_match_all but it was in vain..
Please help..

SOLUTION

Beverley Portlock

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Sudhindra A N

ASKER

hi bportlock, thanks for your reply..
Your code is nearer to my solution.
what is need is the value of the attribute "act" of "target" tag and not the tag contents. and this "target" tag should come after "h3" tag.

Beverley Portlock

OK, how is this?

<?php

$test = '<h3 attr="e"><target act="filename1">test</target></h3>
                      <target act="filename2">myfile.ext</target>
         <h3><target act="filename3">myfile.ext</target></h3>';

preg_match_all( '#<h3.*?><target.*?act="([^"]*?)">[^<]*?</target>#s', $test, $matches );

echo "<pre>";
print_r( $matches[1] );
echo "</pre>";

Open in new window

Note that the middle test has no h3 tags and is skipped in the output like so

Array
(
[0] => filename1
[1] => filename3
)

ASKER CERTIFIED SOLUTION

Ray Paseur

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Beverley Portlock

Ray said: "Personally,l I find it easier to understand REGEX if I write it out on several lines with comments"

I find that just makes it even less comprehensible - something that I never thought was possible with regexes...

;-)

Ray Paseur

@bportlock: Yes, REGEX is an excursion through the looking glass into a land where the entire language is made up of almost nothing but punctuation. Who would think of such a thing? Oh, a 1950's mathematician. Figures.
http://en.wikipedia.org/wiki/Regular_expression

Best to all, over and out, ~Ray

tel2

Nice work, Ray. Well layed out (even if your comments are SHOUTING at me).

BTW, do you know why people (including you, I see), generally use "//", as opposed to the shorter "#", for comments in PHP?

Beverley Portlock

"BTW, do you know why people (including you, I see), generally use "//", as opposed to the shorter "#", for comments in PHP?"

Speaking for myself, I came to PHP via C++ and Java and just carried the habit of using //

Sudhindra A N

ASKER

awesome answers... thanks guys.....

Ray Paseur

Thanks for the points. @tel2: No real reason for // vs # except habit. The value of having SHOUTING COMMENTS is twofold: It makes them easier to see when I glance at my code (and I can search with case-sensitive inspections). And it tells novice programmers how IMPORTANT COMMENTS CAN BE!

tel2

Thanks Ray.
Well you're not alone in your habit, coz I don't recall ever seeing PHP code with "#" for comments, and I wonder how that habit started, if "#" is a valid (and more concise) alternative. Unless people find "//" easier to spot, of course. Or was "#" a more recent addition to PHP, than "//"?
I don't know much PHP, but Perl and shell scripts use "#", so that's what I tend to use in PHP.