取得完整浮點數

function getTime(){
    list($usec, $sec) = explode(" ", \microtime());
    return $sec+$usec;
}
function calculate($start, $end){
    echo "執行秒數: " . sprintf("%.10f", $end-$start);
}
$start = getTime();

$end = getTime();
calculate($start, $end);