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Help with preg_match()

Hello Experts!

Can anyone tell me how I could set up preg_match($pattern, $subject, $matches) to be able to capture only the digits between an underscore character ("_") and an image extension (".jpg" for example)? In other words, let's say I have an image labeled "img_20131009_12.jpg". How would I be able to make it so that $matches[0] contains "12"?

SOLUTION

Ray Paseur

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mvidas

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Ray Paseur

It will depend on your test data, but this shows how you might do it with the regular expression. Look in $mat[1] instead of [0].

<?php // RAY_temp_omniunlimited.php
error_reporting(E_ALL);

$str = 'img_20131009_12.jpg';

$rgx
= '#'         // REGEX DELIMITER
. 'img_'      // LITERAL STRING
. '\d{8}'     // EIGHT DIGITS
. '_'         // LITERAL STRING
. '('         // START CAPTURE GROUP
. '[^.]{1,3}' // ANYTHING BUT DOT, UP TO THREE
. ')'         // END GROUP
. '#'         // REGEX DELIMITER
;

preg_match($rgx, $str, $mat);
var_dump($mat);

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OmniUnlimited

ASKER

Outstanding gentlemen! The perfect answers in record time!

@Ray: As always, you astound me with your intimate knowledge of PHP. Thank you for your more efficient solution. But, since the question asked for help with preg_match, I'm afraid it is only fair to award mvidas the lion's share of the points for correctly answering the question.

@mvidas: Works like a charm. Thanks!

mvidas

Glad to have helped! FYI, if you want to extract more data (like the date, extension, etc), you can surround that area with parenthesis to create another submatch.
If your pattern is /^img_(\d{8})_(\d+).([a-z0-9])+$/i then your $matches would be
[0] img_20131009_12.jpg
[1] 20131009
[2] 12
[3] jpg

You can of course change that however needed if you want to further break it down.
Matt

OmniUnlimited

ASKER

Wow mvidas, that info is also very helpful!

Sorry I don't have any more points to award... :(

mvidas

Don't be sorry at all, just glad I could help :)