c++ - Calculate checksum of a point number -

i'm trying create function able calculate checksum of number, including floating point numbers.

for example:

360° = 3+6+0 = 9 180° = 1+8+0 = 9 90° = 9+0 = 9 45° = 4+5 = 9 22.5° = 2+2+5 = 9 11.25° = 1+1+2+5 = 9 5.625° = 5+6+2+5 = 18 = 1+8 = 9 2.8125° = 2+8+1+2+5 = 18 = 1+8 = 9 1.40625 = 1+4+0+6+2+5 = 18 = 1+8 = 9 0.703125 = 0+7+0+3+1+2+5 = 18 = 1+8 = 9 0.3515625 = 0+3+5+1+5+6+2+5 = 27 = 2+7 = 9 0.17578125 = 0+1+7+5+7+8+1+2+5 = 36 = 3+6 = 9 ... 

i wrote little code, calculates checksum of integer:

#include<iostream> using namespace std;  int checksum(int param) {     int sum = 0;      while (param > 0)     {         sum += param % 10;         param /= 10;     }      while (sum > 9) { sum = checksum(sum); }       return sum; }  int main() {     int number = 0;      cout<<"enter number:"<<endl;     cin>> number;      cout<< checksum(number);      cin.get(); cin.get();     return 0; } 

how can improve it, works floating point numbers?

background

i try find out if true pattern example continue forever result of 9 checksum.

update

unfortunattely c++ not precise enough project. e.g. if calculate 0.703125 / 2 result 0.3515625, in c++ result 0.351563. code: http://www.pasteall.org/61345/cpp

let want calculate checksum upto 5 decimal point of floating point number multiply floating point number 100000 , take 'floor' calculate checksum function.

edit

as float , double has precession problem it's better not use them calculate checksum more digit(15 digit double). more digit use string representation of floating number.