内存中int类型的大小端存储

环境：VC6.0

typedef union
{
 unsigned char pos[4];
 unsigned int id;
}ID;

ID id;

文件第一行：0x01,0x02,0x03,0x04, "1st at " "a  b"

问题：fscanf(fp, "%x,%x,%x,%x,", &id.pos[0], &id.pos[1], &id.pos[2], &id.pos[3]);
结果id.id = 0x04030201; 这可能是因为反了

于是：fscanf(fp, "%x,%x,%x,%x,", &id.pos[3], &id.pos[2], &id.pos[1], &id.pos[0]);

结果id.id = 0x00000004; 奇怪了

找原因：  fscanf(fp, "%x,", &id.pos[3]);    //执行完该语句，id.id = 0x01000000

              fscanf(fp, "%x,", &id.pos[2]);    //执行完该语句，id.id = 0x00020000

              fscanf(fp, "%x,", &id.pos[1]);    //执行完该语句，id.id = 0x00000300

              fscanf(fp, "%x,", &id.pos[0]);    //执行完该语句，id.id = 0x00000004
为什么呢？地址对齐？
              fscanf(fp, "%x,", &id.pos[0]);    //执行完该语句，id.id = 0x00000001

              fscanf(fp, "%x,", &id.pos[1]);    //执行完该语句，id.id = 0x00000201

              fscanf(fp, "%x,", &id.pos[2]);    //执行完该语句，id.id = 0x00030201

              fscanf(fp, "%x,", &id.pos[3]);    //执行完该语句，id.id = 0x04030201

虽然结果反了，但工作正常。

&id.pos[3]的地址>......>&id.pos[0]的地址

              id.id = 0x55555555;
              fscanf(fp, "%x,", &id.pos[3]);    //执行完该语句，id.id = 0x01555555

              fscanf(fp, "%x,", &id.pos[2]);    //执行完该语句，id.id = 0x00025555

              fscanf(fp, "%x,", &id.pos[1]);    //执行完该语句，id.id = 0x00000355

              fscanf(fp, "%x,", &id.pos[0]);    //执行完该语句，id.id = 0x00000004

我想原因找到了：
memory address：   00         01         02         03        04         05         06    

                               pos[0]  pos[1]  pos[2]  pos[3]       n           n           n

给pos[3]赋0x01                                               01         00         00         00

给pos[2]赋0x02                                   02        00         00         00            

给pos[1]赋0x03                      03         00        00         00

给pos[0]赋0x04         04         00        00         00
所以最终结果总是04。上述结果是我的推论。
修改输入0x01010101,0x02020202,0x03030303,0x04040404, "1st at " "a  b"
进行调试，打开内存视图进行观察，推论是正确的。

结论就是%x返回的可能是4字节int，或其它。如何处理将%x返回成一个字节的呢？