计算任意精确的小数值

#include <stdio.h>
int main()
{
    double n, m;
    int s[20], i = 0, j, k, l, t = 0, r, b = 0, p = 0;
    scanf("%lf%lf", &n, &m);
    k = n; l = m;//k分子,l分母
    while (l != 1)
    {
        if ( l% 2 == 0)
            l = l / 2;
        else if (l % 5 == 0)
            l = l / 5;
        else break;
    }
    while (k < l)
    {
        k *= 10; t++;
    }
    r = k;
    if (l != 1) {
        while (i != 20)//计算20位小数
        {
            while (b > 1) { s[i] = 0; b--; i++; }
            s[i] = r / l;
            r = r % l;
            b = 0;
            while (r < l) {r *= 10; b++;}
            i++;
        }        
        while (t > 0) { l *= 10; t--; }
        printf("%d.",k/l);        
        for (i = 0; i < 20; i++)
        {
            printf("%d", s[i+t]);
        }
    }        
    else printf("%g\n", n/m);
    return 0;
}