这是我尝试编写的类似于 Excel ROUNDUP 函数的解决方案。我尝试覆盖了负小数、负数位数(是的,Excel 支持这种情况)和大的小数值等情况。
public static decimal RoundUp(decimal number, int digits)
{
if (digits > 0)
{
var absNumber = Math.Abs(number);
var absNumberIntegralPart = Decimal.Floor(absNumber);
var fraction = (absNumber - absNumberIntegralPart);
var tenPower = (decimal)Math.Pow(10, digits);
var fractionRoundedUp = Decimal.Ceiling(fraction * tenPower) / tenPower;
return Math.Sign(number) * (absNumberIntegralPart + fractionRoundedUp);
} else if (digits == 0)
{
return Math.Sign(number) * Decimal.Ceiling(Math.Abs(number));
} else if (digits < 0)
{
var absNumber = Math.Abs(number);
var absNumberIntegralPart = Decimal.Floor(absNumber);
var tenPower = (decimal)Math.Pow(10, -digits);
var absNumberIntegraPartRoundedUp = Decimal.Ceiling(absNumberIntegralPart / tenPower) * tenPower;
return Math.Sign(number)*absNumberIntegraPartRoundedUp;
}
return number;
}
[TestMethod]
public void Can_RoundUp_Correctly()
{
Assert.AreEqual(1.466m, MathExtensions.RoundUp(1.4655m, 3));
Assert.AreEqual(-1.466m, MathExtensions.RoundUp(-1.4655m, 3));
Assert.AreEqual(150m, MathExtensions.RoundUp(149.001m, 0));
Assert.AreEqual(-150m, MathExtensions.RoundUp(-149.001m, 0));
Assert.AreEqual(149.2m, MathExtensions.RoundUp(149.12m, 1));
Assert.AreEqual(149.12m, MathExtensions.RoundUp(149.12m, 2));
Assert.AreEqual(1232m, MathExtensions.RoundUp(1232, 2));
Assert.AreEqual(200m, MathExtensions.RoundUp(149.123m, -2));
Assert.AreEqual(-200m, MathExtensions.RoundUp(-149.123m, -2));
Assert.AreEqual(-20m, MathExtensions.RoundUp(-12.4655m, -1));
Assert.AreEqual(1.67m, MathExtensions.RoundUp(1.666666666666666666666666666m, 2));
Assert.AreEqual(1000000000000000000000000000m, MathExtensions.RoundUp(999999999999999999999999999m, -2));
Assert.AreEqual(10000000000000m, MathExtensions.RoundUp(9999999999999.999m, 2));
}