Working with "multiple" select

In my profile advanced search i have an mutiple se开发者_运维技巧lect type..

<form method="POST">
                     <select size="6" name="Cities" multiple="multiple" id="Cities">
    <option value="0">All</option>
    <option value="1">City1</option>
    <option value="2">city2</option>
    <option value="3">city3</option>
    <option value="4">city4</option>
    <option value="5">city5</option>
</select>
</form>

How do I use it, I mean how should i call what they have chosed...As you can choose one or more options (by holding in control, or just holding in mouseclick and point to other options).

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Give it the name Cities[] instead of Cities, and you'll have an array in $_POST['Cities'] on submit.

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google helps http://www.onlinetools.org/tricks/using_multiple_select.php