您的name
声明,需要name="test[]"
.
<select name="test[]" id="test" multiple>
<option value="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value="opel">Opel</option>
<option value="audi">Audi</option>
</select>
update_usermeta( $new_user, \'test\', $_POST[\'test\'] );
编辑回复:您的评论,
$meta = get_user_meta($user_id, \'test\');
foreach ($meta as $key => $value) {
echo $value;
}