regex help, preg_replace

[mapunk]

I've tried working on this for a pretty long time, but I'm new to regular exprsesions so I really have no idea how to do this.

Let's say I have a string like the one below.  I have an array of the usernames...Let's call it $user_array.  How would I go about searching for, and replacing the string under each user with a string called $replacement?  Or better yet, how would I just capture the text for each user using preg_match?  It needs to be able to capture multiple lines and any character thrown it's way.  I don't need the whole logic behind it, just the preg_replace/preg_match statement.  Thanks guys

[quote]
[username=User1]
Some notes on this user go here
[username=User2]
More notes
on user two go
here
[username=User3]
These are notes
that I have kept for
this
particular user
[/quote]

[effigy]

[code]
<pre>
<?php

$data = <<<DATA
[username=User1]
Some notes on this user go here
[username=User2]
More notes
on user two go
here
[username=User3]
These are notes
that I have kept for
this
particular user
DATA;
$data_array = explode("\n", $data);
### The above can be handled with the file function.

### The name.
$user = '';
### The data.
$user_data = '';
### The result.
$result = array();
foreach ($data_array as $piece) {
### If a user name is found...
if (preg_match('/\[username=(.+?)\]/',$piece, $matches)) {
### ...and there is data...
if ($user_data) {
### ...add the user to the array with their data...
$result[$user] = $user_data;
### ...and empty the data.
$user_data = '';
}
### ...set the new user that was found.
$user = $matches[1];
}
### No user name was found, tack onto the data.
else {
$user_data .= $piece;
}
}
### "Flush."
$result[$user] = $user_data;

print_r($result);
?>
</pre>
[/code]

[mapunk]

Thanks a lot, I'll check it out and let you know how it goes  :)