Question

I have a Double value:

double a = 4.5565;

What is the easiest way to calculate the number of digits after the decimal point (4 in this case).

I know that I can convert to string and do a split and take the length. But is there an easier way?

Answer 1

There’s no easy way, especially since the number of digits mathematically speaking might be far more than displayed. For example, 4.5565 is actually stored as 4.556499999999999772626324556767940521240234375 (thanks to harold for calculating that). You’re very unlikely to find a useful solution to this problem.

EDIT

You could come up with some algorithm that works like this: if, as you calculate the decimal representation, you find a certain number of 9s (or zeros) in succession, you round up (or down) to the last place before the series of 9s (or zeros) began. I suspect that you would find more trouble down that road than you would anticipate.