mixed precision

a.c

void main()
{
        static long l = -2L;
        static double d = 2.2;
        static float f = 2.2;
        d /= f;
        printf("%ld\n",(l));
        printf("%lf\n",d);
        printf("%lf\n",(l -= d));
        l -= d;
        l -= d;
        l -= d;
        printf("hello 3 times\n");
        printf("%ld\n",l);
}

gcc -O0 -g a.c

result:

-2
1.000000
1.000000
hello 3 times
-2

reason:

(gdb) p d
$2 = 0.99999997832558429
(gdb)

l -= d
	l convert to double
	two double substraction
	convert to long