Conversion from double to int in C

Question

#include<stdio.h>
int main(){
double amount;
int dollar,cent;
scanf("%lf",&amount);
dollar=amount;
cent=(amount-dollar)*100;
printf("%d dollar(s) and %d cent(s)\n",dollar,cent);
return 0;
}

In this program, if I input 12.50; it prints "12 dollar(s) and 50 cent(s)". But if I input 12.01; it prints "12 dollar(s) and 0 cent(s)" instead of "12 dollar(s) and 1 cent(s)". Why is that? Is there any conversion problem between double and int? Or this code is wrong?

And,
When amount = 12.01; it prints 0 cent(s)
When amount = 12.02; it prints 1 cent(s)
When amount = 12.03; it prints 2 cent(s)
When amount = 12.04; it prints 3 cent(s)... which are wrong.
But,
When amount = 12.05; it prints 5 cent(s)
When amount = 12.06; it prints 6 cent(s)
When amount = 12.07; it prints 7 cent(s)... which are correct.

I am a beginner so I couldn't solve this issue.
Thanks in advance.

Answer 1

When double is converted to int, it is truncated but not rounded.

(12.01 - 12)*100 is not equal to one due to limited precision of double (it equals ~ 0.99999...), so the result will be 0.

use round function to round result:
cent=round((amount-dollar)*100);