C - floor of double moduls integer

Question

I need to do the following equation floor(e%100000) where e is a double. I know mod only accepts int values, how do I go about achieving this same result?

Thanks

Answer 1

Use the fmod() function instead of %. It accepts double parameters, and returns a double result.

Answer 2

Why don't you take the floor first, then mod, ie. floor(e) % 100000 ?

Perhaps I've misunderstood what you're trying to achieve. Could you give an example of the input and output you expect?

Answer 3

use fmod

Answer 4

You could use division to make the equivalent of modulo:

double e = 1289401004400.589201;
const double divisor = 100000.0;
double remainder = e - floor(e / divisor) * divisor;
double result = floor(remainder);
printf("%f\n", result);

This prints

4400.000000

Of course, this is much slower than any built-in modulo...

You could also just use fmod, as Anders K. suggested :)

Edit

Fixed std::cout (C++) reference to use printf (C). Fixed change to output. Now it is purely C.