Exclude character from being returned in array - php

Question

I have the following regex function:
function getMatches($string_content) {
$matches = array();
preg_match_all('/#([A-Za-z0-9_]+)/', $string_content, $matches);
return $matches;
}
Right now, it returns an array like this:
Array (
[0] => Array (
[0] => #test
[1] => #test2
)
[1] => Array (
[0] => test
[1] => test2
)
)
How can I make it only return the matches without the # symbol?

Answer 1

Return $matches[1] instead of $matches.
That will give you the first capture group instead of all matches.

Answer 2

With this small tweak (you can inspect the matches in the regex demo):
preg_match_all('~#\K\w+~', $string_content, $matches);
Explanation
In your original regex, the parentheses around ([A-Za-z0-9_]+) create a capture group. This is why the array contains a second element with index #1: this element contains the Group 1 captures.
\w is equivalent to [A-Za-z0-9_]
The \K tells the engine to drop what was matched so far from the final match it returns. It is more efficient than using a lookbehind (?<=#)
The ~ is just a small esthetic tweak—you can use any delimiter you like around your regex patttern.

Answer 3

Just use \K in your regex to avoid # in the final result and you don't need to capture anything,
preg_match_all('~#\K[A-Za-z0-9_]+~', $string_content, $matches);
OR
Use a lookbehind,
preg_match_all('~(?<=#)[A-Za-z0-9_]+~', $string_content, $matches);
DEMO
Explanation:
(?<=#) REgex engine sets the matching marker just after to the # symbol.
[A-Za-z0-9_]+ Matches one or more word characters.

Answer 4

You don't need any change in your regular expression, simply refer to capturing group #1, which would be $matches[1] to print the match result from your capturing group, excluding # from your array matches.
Your code would look like this:
function getMatches($string_content) {
preg_match_all('/#([A-Za-z0-9_]+)/', $string_content, $matches);
return $matches[1];
}
print_r(getMatches('foo bar #test baz #test2 quz'));
Output
Array
(
[0] => test
[1] => test2
)