PHP preg_match_all not returning values

Question

I have a regex that checks for a username between 4 and 25 characters in length, followed by any optional spacebars and/or a single comma. As you may have guessed this is to be used for sending personal messages to several people by typing something like "Username1, Username2, Username3" ect.

$rule = "%^\w{4,25}( +)?,?( +)?$%";
preg_match_all($rule, $sendto, $out);
foreach($out[1] as $match) {
    echo $match;
}

The regex seems to be doing its job, although when I use preg_match_all(), and attempt to sort through all the values, it will not echo anything to the browser. I suspect that I am misunderstanding something about preg_match_all, since my regex seems to be working.

you should test if preg_match_all() was successful or not before attempting to consume $out. — Scuzzy
– Scuzzy, Commented May 3, 2016 at 0:32

Pedro Lobito · Accepted Answer · 2016-05-03 00:39:25Z

3

Your regex is missing a capture group ([\w]{4,25}) on the usernames, try this:

<?
$users = "Username1, Username2      , Username3       ";
preg_match_all('/([\w]{4,25})(?:\s+)?,?/', $users, $result, PREG_PATTERN_ORDER);
foreach($result[1] as $user) {
    echo $user;
}
/*
Username1
Username2
Username3
*/

Live Demo

Regex Explanation:

([\w]{4,25})(?:\s+)?,?

Match the regex below and capture its match into backreference number 1 «([\w]{4,25})»
   Match a single character that is a “word character” (Unicode; any letter or ideograph, any number, underscore) «[\w]{4,25}»
      Between 4 and 25 times, as many times as possible, giving back as needed (greedy) «{4,25}»
Match the regular expression below «(?:\s+)?»
   Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
   Match a single character that is a “whitespace character” (any Unicode separator, tab, line feed, carriage return, vertical tab, form feed, next line) «\s+»
      Between one and unlimited times, as many times as possible, giving back as needed (greedy) «+»
Match the character “,” literally «,?»
   Between zero and one times, as many times as possible, giving back as needed (greedy) «?»

edited May 3, 2016 at 0:39

answered May 3, 2016 at 0:32

Pedro Lobito

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1 Comment

Brandon Stephen Hayden Over a year ago

Ah, that fixed my problem. I appreciate the help, I am new to regex and it can be overwhelming. I've been trying to fix the wrong thing for the last several hours it seems.

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