Thread: why big numbers change in floating-point variables?

hi i don't know why but some of the values change on their own when i run this code. why?

Code:

#include <stdio.h>
#include <math.h>

int main(void)
{
    double a = 111 * pow(10,20);
    double b = 128 * pow(10,20);
    double c = 255 * pow(10,20);
    double d = 256 * pow(10,20);
    double e = 10 * pow(10,20);

    printf("%f\n%f\n%f\n%f\n%f\n", a,b,c,d,e);
    return 0;
}

my output:

Code:

11100000000000001048576.000000
12800000000000000000000.000000
25500000000000001048576.000000
25600000000000000000000.000000
1000000000000000000000.000000

if you look at the output the first and third value changed on their own.