Get number of digits before decimal point

c# numbers decimal
fasadat picture fasadat · Feb 4, 2014 · Viewed 24k times · Source

I have a variable of decimal type and I want to check the number of digits before decimal point in it. What should I do? For example, 467.45 should return 3.

Answer

astef picture astef · Feb 4, 2014

Solution without converting to string (which can be dangerous in case of exotic cultures):

static int GetNumberOfDigits(decimal d)
{
    decimal abs = Math.Abs(d);

    return abs < 1 ? 0 : (int)(Math.Log10(decimal.ToDouble(abs)) + 1);
}

Note, that this solution is valid for all decimal values

UPDATE

In fact this solution does not work with some big values, for example: 999999999999998, 999999999999999, 9999999999999939...

Obviously, the mathematical operations with double are not accurate enough for this task.

While searching wrong values I tend to use string-based alternatives proposed in this topic. As for me, that is the evidence that they are more reliable and easy-to-use (but be aware of cultures). Loop-based solutions can be faster though.

Thanks to commentators, shame on me, lesson to you.

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