c - Why we can't use operator % for float and double type operands?

Question

I am new to C/C++, so I have a couple of questions about a basic type:

1. I have read somewhere that the operator % can't be applied to float or double type operands. Then how can I check the divisibility of float or double type variables? I have shown my program with error below:

   #include <stdio.h>
   
   int main()
   {
       double n,k,t,i;
       int j=0;
       scanf("%f %f",&n,&k);
       i=0;
       while(i<n)
       {
           scanf("%f",&t);
           if(t%k==0)   /* error:invalid operands to binary %  */
               j++;
           i++;
       }
       printf("%d",j);
       return 0;
   }
   

2. If a positive integer has a range up to 10^9, which qualifier should I use or how to achieve such a large range?

Answer 1

then how can i check the divisibility of float or double type variables. ??`

Use fmod. % only work with integer operands. % does not work with floating point values because C already provides the fmod library function.