int、short、long、long long、unsigned、unsigned short、unsigned long、unsigned long long 长度

类型标识符	32位机器所占字节长度	64位机器所占字节长度	格式化输出
int	4	4	%d
short	2	2	%d
long	4	8	%ld
long long	8	8	%lld
unsinged	4	4	%u
unsinged short	2	2	%u
unsiged long	4	8	%lu
unsigned long long	8	8	%llu

综上所述: 32位机器和64位机器比较，对于long和unsigned long类型，所占用的空间是不一样的，从代码可移植性考虑，
定义变量最好明确所需长度，选用合适的变量类型。(注：这只是常见而已，并不代表所有的32位机器和64位机器均是这样，所以选用比较明确的类型，更合理高效)

#include 
#include 

int main()
{
	int i_a = 1;
	short s_a = 2;
	long l_a = 3;
	long long ll_a = 4;
	unsigned u_a = 5;
	unsigned short us_a = 6;
	unsigned long ul_a = 7;
	unsigned long long ull_a = 8;

	printf(" i_a = %d, sizeof(i_a) = %u\n", i_a, sizeof(i_a));
	printf(" s_a = %d, sizeof(s_a) = %u\n", s_a, sizeof(s_a));
	printf(" l_a = %ld, sizeof(l_a) = %u\n", l_a, sizeof(l_a));
	printf(" ll_a = %lld, sizeof(ll_a) = %u\n", ll_a, sizeof(ll_a));
	printf(" u_a = %u, sizeof(u_a) = %u\n", u_a, sizeof(u_a));
	printf(" us_a = %u, sizeof(us_a) = %u\n", us_a, sizeof(us_a));
	printf(" ul_a = %lu, sizeof(ul_a) = %u\n", ul_a, sizeof(ul_a));
	printf(" ull_a = %llu, sizeof(ull_a) = %u\n", ull_a, sizeof(ull_a));

	return 1;
}

X86 VS测试结果: