这是你的答案
$current_date = date('d-M-Y g:i:s A');
echo $current_date."<br/>";
$current_time = strtotime($current_date);
$frac = 900;
$r = $current_time % $frac;
$new_time = $current_time + ($frac-$r);
$new_date = date('d-M-Y g:i:s A', $new_time);
echo $new_date."<br/>";
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