Get number of digits before decimal point

Question

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

Answer 1

This would be the Java solution

public class test {
    public static void main(String args[]) {
        float f = 1.123f;
        int a = (int) f;
        int digits = 0;
        while (a > 0) {
            digits++;
            a=a/10;
        }
        System.out.println("No Of digits before decimal="+digits);
    }
}

Answer 2

You could do this by rounding the number, then getting the length of the new number. You could do it like this:

var number = 476.43;
var newNumber = Math.round(number);

//get the length of the rounded number, and subtract 1 if the
//number is negative (remove the negative sign from the count)
int digits = newNumber.ToString().Length - (number < 0 ? 1 : 0);

Answer 3

Here's a recursive example (mostly for fun).

void Main()
{
    digitCount(0.123M); //0
    digitCount(493854289.543354345M); //10
    digitCount(4937854345454545435549.543354345M); //22
    digitCount(-4937854345454545435549.543354345M); //22
    digitCount(1.0M); //1
    //approximately the biggest number you can pass to the function that works.
    digitCount(Decimal.MaxValue + 0.4999999M); //29
}

int digitCount(decimal num, int count = 0)
{
    //divided down to last digit, return how many times that happened
    if(Math.Abs(num) < 1)
        return count;
    return digitCount(num/10, ++count); //increment the count and divide by 10 to 'remove' a digit
}

Answer 4

This will do if you really don't want to use the Log method (which IMO is the best way). It's about the clearest way I can think of of doing this using ToString():

Math.Abs(val).ToString("f0", CultureInfo.InvariantCulture).Length

Or alternatively, if you don't want to count 0.123M as having one digit:

Math.Abs(val).ToString("#", CultureInfo.InvariantCulture).Length

Answer 5

var sep = Convert.ToChar(CultureInfo.CurrentCulture.NumberFormat.NumberDecimalSeparator);
var count = d.ToString().TakeWhile(c => c != sep).Count();

Answer 6

In order to get an accurate and culturally agnostic answer I do the following:

1. Use System.Numerics.BigInteger, whose constructor accepts a decimal and doesn't seem to produce any rounding errors.
2. Use BigInteger.Abs() to remove any sign.
3. Use BigInteger.ToString() with the "#" format to suppress any separators that might occur.

Code

decimal num = 123213123.123123M;
int length = BigInteger.Abs((BigInteger)num).ToString("#").Length;