Finding values in a string via regex in php - php

Question

I am trying to get information out of a textarea that contains certain strings (e.g. [name]) and find each item encased in the square brackets using regex patterns (currently tried using preg_match, preg_split, preg_quote, preg_match_all). It seems that the problem is in my regex pattern that I am providing for it.
My current regex:
$menuItems = preg_match_all('/[^[][([^[].*)]/U', $_SESSION['emailBody'], $menuItems);
I have tried many other patterns e.g.
/(?[...]\w+): (?[...]\d+)/
Any help that can be provided with this is greatly appreciated.
EDIT:
Sample input:
[email] address [to] name [from] someone
Message displayed on var_dump of the $menuItems variable:
array(1) { [0]=> string(0) "" }
EDIT 2:
Thank you to everyone for the help and support with this, I am pleased to say that it is all up and running perfectly!

Answer 1

From the comment stream above, you can simplify the regular expression as follows:
preg_match_all('/\[(.*)\]/U', $_SESSION['emailBody'], $menuItems);
One thing to note:
preg_match_all() fills the array in its 3rd parameter with the results of the matches. Your example line then overwrites this array with the result of preg_match_all() (an integer).
You should then be able to iterate over the results by using the following loop:
foreach ($menuItems[1] as $menuItem) {
// ...
}

Answer 2

Escape the square brackets and remove the dot:
$menuItems = preg_match_all('/[^[]\[([^[]*)\]/U', $_SESSION['emailBody'], $menuItems);
// here __^ __^ ^
preg_match_all doesn't return a string. You have to add an array for the last parameter:
preg_match_all('/\[([^[\]]*)\]/U', $_SESSION['emailBody'], $matches);
The matches are in the array $matches
print_r($matches);
Working example:
$str = '[email] address [to] name [from] someone';
preg_match_all('/\[([^[\]]*)\]/U', $str, $matches);
print_r($matches);
Output:
Array
(
[0] => Array
(
[0] => [email]
[1] => [to]
[2] => [from]
)
[1] => Array
(
[0] => email
[1] => to
[2] => from
)
)

Answer 3

Here is a simple solution. This regex will capture all items encased in brackets along with brackets as well.
If you don't want brackets in result change regex to $regex = "/(?:\\[(\\w+)\\])/mi";
$subject = "[email] address [to] name [from] someone";
$regex = "/(\\[\\w+\\])/mi";
$matches = array();
preg_match_all($regex, $subject, &$matches);
print_r($matches);