Question

I’m trying to create a decimal representation of a big integer when it’s divided by something. The follwoing is the code which does it, basically I want the precision to be of 2 places.

    public string GetDecimal(BigInteger bigInteger,int divisor)
    {
        var remainder   = BigInteger.Remainder(bigInteger, divisor);
        var dividend    = BigInteger.Divide(bigInteger, divisor);

        var d = ((double)remainder / divisor);
        var decimalPart = Math.Round(d, 2);
        var retValue = dividend + decimalPart.ToString(".00");
        return retValue;
    }
}

Is there a better way of doing this please?

Thanks,
-Mike

Answer 1

You should probably not convert the types and do the long division on your own. This should work with any BigInteger value.

I’m sure there’s room for improvement here…

public string GetDecimal(BigInteger bigInteger, int divisor)
{
    BigInteger remainder;
    var quotient = BigInteger.DivRem(bigInteger, divisor, out remainder);

    const int decimalPlaces = 2;
    var decimalPart = BigInteger.Zero;
    for(int i = 0; i < decimalPlaces; i++)
    {
        var div = (remainder*10)/divisor;

        decimalPart *= 10;
        decimalPart += div;

        remainder = remainder*10 - div*divisor;
    }

    var retValue = quotient.ToString() + "." + decimalPart.ToString(new string('0', decimalPlaces));
    return retValue;
}