如何在C中显示无符号long long的最大值?

我在这里做错什么了?

$ cat size.c
#include<stdio.h>
#include<math.h>

int main() {

printf ("sizeof unsigned int = %d bytes.\n", sizeof(unsigned int));
printf ("sizeof unsigned long long = %d bytes.\n", sizeof(unsigned long long));

printf ("max unsigned int = %d\n", (int)(pow(2, 32) - 1));
printf ("max unsigned long long = %lld\n", (unsigned long long)(pow(2, 64) - 1));

}
$ gcc size.c -o size
$ ./size
sizeof unsigned int = 4 bytes.
sizeof unsigned long long = 8 bytes.
max unsigned int = 2147483647
max unsigned long long = -1
$ 

我在期待 18446744073709551615 -1 在最后一行。

^32个 -1,应该是4294967295,而不是2147483647。现在事情变得更有意义了。