Get number of significant digits to the right of decimal point in c# Decimal

Question

I would like a c# function with this signature:

int GetSignificantNumberOfDecimalPlaces(decimal d)

It should behave as follows when called:

    GetSignificantNumberOfDecimalPlaces(2.12300m); // returns 3
    GetSignificantNumberOfDecimalPlaces(2.123m);   // returns 3
    GetSignificantNumberOfDecimalPlaces(2.103450m);  // returns 5
    GetSignificantNumberOfDecimalPlaces(2.0m); // returns 0
    GetSignificantNumberOfDecimalPlaces(2.00m); // returns 0
    GetSignificantNumberOfDecimalPlaces(2m); // returns 0

i.e. for a given decimal, i want the number of significant decimal places to the right of the decimal point. So trailing zeros can be ignored. My fallback is to turn the decimal into a string, trim trailing zeros, and get the length this way. But is there a better way ?

NOTE: I may be using the word "significant" incorrectly here. The required return values in the example should hopefully explain what i'm after.

Answer 1

Some very good answers here Parse decimal and filter extra 0 on the right?

decimal d = -123.456700m;

decimal n = d / 1.000000000000000000000000000000m;  // -123.4567m

int[] bits = decimal.GetBits(n);

int count = bits[3] >> 16 & 255; // 4        or byte count = (byte)(bits[3] >> 16);

Answer 2

I can help you to do the same with few string operations,This may be a workaround solution for your problem, anyway consider this suggestion, hope that it would help you

static int GetSignificantNumberOfDecimalPlaces(decimal d)
{
    string inputStr = d.ToString(CultureInfo.InvariantCulture);
    int decimalIndex = inputStr.IndexOf(".") + 1;
    if (decimalIndex == 0)
    {
        return 0;
    }
    return inputStr.Substring(decimalIndex).TrimEnd(new[] { '0' }).Length;

}

Working Example with all the specified inputs