也许您在寻找BigRational吗?Microsoft在其CodePlex的BCL项目下发布了它。实际不确定如何或是否会满足您的需求。
它保持为有理数。您可以通过强制转换或某种乘法来获得带有十进制值的字符串。
var r = new BigRational(5000, 3768);
Console.WriteLine((decimal)r);
Console.WriteLine((double)r);
或使用简单的(ish)扩展方法,例如:
public static class BigRationalExtensions
{
public static string ToDecimalString(this BigRational r, int precision)
{
var fraction = r.GetFractionPart();
// Case where the rational number is a whole number
if(fraction.Numerator == 0 && fraction.Denominator == 1)
{
return r.GetWholePart() + ".0";
}
var adjustedNumerator = (fraction.Numerator
* BigInteger.Pow(10, precision));
var decimalPlaces = adjustedNumerator / fraction.Denominator;
// Case where precision wasn't large enough.
if(decimalPlaces == 0)
{
return "0.0";
}
// Give it the capacity for around what we should need for
// the whole part and total precision
// (this is kinda sloppy, but does the trick)
var sb = new StringBuilder(precision + r.ToString().Length);
bool noMoreTrailingZeros = false;
for (int i = precision; i > 0; i--)
{
if(!noMoreTrailingZeros)
{
if ((decimalPlaces%10) == 0)
{
decimalPlaces = decimalPlaces/10;
continue;
}
noMoreTrailingZeros = true;
}
// Add the right most decimal to the string
sb.Insert(0, decimalPlaces%10);
decimalPlaces = decimalPlaces/10;
}
// Insert the whole part and decimal
sb.Insert(0, ".");
sb.Insert(0, r.GetWholePart());
return sb.ToString();
}
}
如果它超出小数或双精度范围,则将它们转换为各自的值0.0。另外,当结果超出其范围时,强制转换为小数将导致OverflowException
抛出。
我编写的扩展方法(这可能不是计算分数的十进制表示的 最佳 方法)将以无限的精度将其准确转换为字符串。但是,如果数字小于要求的精度,则它将返回0.0,就像十进制或双精度一样。