對(duì)于這段代碼：$value = 200.1;$denominator = 0.1;echo "value: $value\n";echo "denominator: $denominator\n";$resultInt = ($value / $denominator);echo "($value / $denominator) = ";printf ("%f\n", $resultInt);$resultInt = (int) ($value / $denominator);echo "(int) ($value / $denominator) = ";printf ("%f\n", $resultInt);$resultInt = floor($value / $denominator);echo "floor($value / $denominator) = ";printf ("%f\n", $resultInt);$resultInt = floor((int) ($value / $denominator));echo "floor((int) ($value / $denominator)) = ";printf ("%f\n", $resultInt);$resultInt = floor((float) 2001);echo "floor((float) 2001) = ";printf ("%f\n", $resultInt);$resultInt = round($value / $denominator, PHP_ROUND_HALF_DOWN);echo "round($value / $denominator, PHP_ROUND_HALF_DOWN) = ";printf ("%f\n", $resultInt);$valueMul = $resultInt * $denominator;if ($valueMul !== $value) {    echo "they are not the same\n";    var_dump($value);    var_dump($valueMul);}$valueDiff = $value - $valueMul;if ($valueDiff !== 0) {    echo "valueDiff is not zero\n";    var_dump($valueDiff);}我有這個(gè)結(jié)果：value: 200.1denominator: 0.1(200.1 / 0.1) = 2001.000000(int) (200.1 / 0.1) = 2000.000000floor(200.1 / 0.1) = 2000.000000floor((int) (200.1 / 0.1)) = 2000.000000floor((float) 2001) = 2001.000000round(200.1 / 0.1, PHP_ROUND_HALF_DOWN) = 2001.000000they are not the samefloat(200.1)float(200.1)valueDiff is not zerofloat(-2.8421709430404E-14)上述所有計(jì)算的預(yù)期結(jié)果是 2001，但在某些情況下它是 2000。我知道由于計(jì)算機(jī)在二進(jìn)制上運(yùn)行，因此分?jǐn)?shù)不會(huì)以小數(shù)形式存儲(chǔ)在變量中。但正如地板手冊(cè)所述：地板 -向下舍入分?jǐn)?shù)因此我期望得到與以下相同的結(jié)果：round(200.1 / 0.1, PHP_ROUND_HALF_DOWN)但 round 按預(yù)期返回 2001，而下限返回 2000（錯(cuò)誤）。你知道為什么嗎？我還發(fā)現(xiàn)這var_debug是不一致的：