一、定義
在VC6.0的Microsoft Visual Studio/VC98/Include/windef.h 裏，定義了BYTE,WORD,DWORD
typedef unsigned long DWORD;
typedef unsigned char BYTE;
typedef unsigned short WORD;
在Visual C++ 6.0中，char型長度爲1字節，short型長度爲2字節，int和long型長度都爲4字節，因此可以認爲BYTE與WORD,DWORD定義的變量分別獲得了1字節，2字節，4字節內存，正與BYTE與WORD,DWORD的字面意義相符。
即:
BYTE=unsigned char(完全等同): 8位
WORD=unsigned short(完全等同): 16位
DWORD=unsigned long(完全等同): 32位
下面是一些平時用得比較少的宏：
二、Window 宏
1.LOBYTE( 從給定16位值中提取低位字節)
BYTE LOBYTE(
WORD wValue // value from which low-order byte is retrieved
);
#define LOBYTE(w) ((BYTE) (w))
如：WORD w=-0x1234;//w在內存中以補碼形式存儲:0xedcc,即0xcc(低地址) 0xed（高地址）
printf("w的低位字節:%x/n",LOBYTE(w));//輸 出：w的低位字節:cc
2.HIBYTE( 從給定16位值中提取高位字節)
BYTE HIBYTE(
WORD wValue // value from which high-order byte is retrieved
);
#define HIBYTE(w) ((BYTE) (((WORD) (w) >> 8) & 0xFF))
如：printf("w的高位字節:%x/n",HIBYTE(w));// 輸出：w的高位字節:ed
3.LOWORD(從給定32位值中提取低位word)
WORD LOWORD(
DWORD dwValue // value from which low-order word is retrieved
);
#define LOWORD(l) ((WORD) (l))
如: DWORD l = 0x12345678;//l在內存中存儲爲:0x78,0x56,0x34,0x12
printf("l的低位字:%x/n",LOWORD(l));// 輸出：l的低位字:5678
4.HIWORD(從給定32位值中提取高位word)
WORD HIWORD(
DWORD dwValue // value from which high-order word is retrieved
);
#define HIWORD(l) ((WORD) (((DWORD) (l) >> 16) & 0xFFFF))
如:printf("l的高位字:%x/n",HIWORD(l));//輸出：l的高位字:1234
5.MAKEWORD(將兩個給定的無符號字符值連接成爲一個16位整數)
WORD MAKEWORD(
BYTE bLow, // low-order byte of short value
BYTE bHigh // high-order byte of short value
);
#define MAKEWORD(a, b) /
((WORD) (((BYTE) (a)) | ((WORD) ((BYTE) (b))) << 8))
如: BYTE bLow=0x34,bHigh=0x12;
printf("MAKEWORD(%x,%x)=%x/n",bLow,bHigh,MAKEWORD(bLow,bHigh));
輸出結果爲: MAKEWORD(34,12)=1234
6.MAKELONG(將兩個給定的16位值連接成爲一個32位整數)
DWORD MAKELONG(
WORD wLow, // low-order word of long value
WORD wHigh // high-order word of long value
);
#define MAKELONG(a, b) /
((LONG) (((WORD) (a)) | ((DWORD) ((WORD) (b))) << 16))
如：WORD vLow=0x5678,vHigh=0x1234;
printf("MAKELONG(%x,%x)=%x/n",vLow,vHigh,MAKELONG(vLow,vHigh));
輸出結果：MAKELONG(5678,1234)=12345678