PHP从分隔字符串创建选项列表而不重复值

I have a string with values (which are suburbs) like so:

$suburbs = "Mawson, Elizabeth, Burnside, Elizbeth, Mawson";

There COULD be double ups in the suburbs that the string contains. I can't change this fact.

What I am trying to do is create an option list for a drop down menu that a user will use. I do not want to display the same suburb twice( or more for that matter).

What I have so far:

$suburbs = "Mawson, Elizabeth, Burnside, Elizbeth, Mawson";
//Explode the suburbs string delimited by a comma
$boom = explode(',', $suburbs);

foreach($boom as $b)
{
$suburbOptionList .= '<option value='.$b.'>'.$b.'</option>';
}
?>
<select> <?php
echo $suburbOptionList;
?>
</select>

I know that this will simply display all of the options but I really don't know how to display each suburb only once. Ive tried a few foreach,and if combinations but they look ugly and work just as bad.

Any help would be appreciated. Cheers in advance!

Pass $boom through array_unique() and you'll be fine.

$bada_boom = array_unique($boom);

P.S.: This will not help if you have typos or variations in duplicates. (Elizbeth != Elizabeth). In that case you will need to get creative.

Also, hw (in comments) made a good point about trimming whitespaces. If the suburbs come from an untrusted source and are improperly formatted, you may need to normalize them. This means trimming whitespaces and normalizing capitals:

$boom = array_walk($boom, 'trim');
$boom = array_walk($boom, 'strtolower');
$bada_boom = array_unique($boom);