如何在头文件中extern位定义变量

只看该作者 · 2011-8-20 10:52

union{
struct
{
uchar ready:1;
uchar guard:1;
uchar speak:1;
uchar shutup:1;
}bit;
uchar  byte;
}memory_addr;  //**标志
#define  memory_flag  memory_addr.byte
#define  ready_flag  memory_addr.bit.ready
#define  guard_flag  memory_addr.bit.guard
#define  speak_flag  memory_addr.bit.speak
#define  shutup_flag  memory_addr.bit.shutup

如上是我在C文件中的定义，在头文件中如何作extern输出。。。网上找了N久也没发现类似例子，特来21IC求教

2万 · 2011-8-20 11:29

你要extern哪个变量？

2万 · 2011-8-20 11:35

//-------------common.h----------------------------------------------------------------
#define             KeySingle          sysflag.bit0
#define             KeyContinue       sysflag.bit1
#define             SetOneClick       sysflag.bit2
#define             WriteEeprom       sysflag.bit3
#define             ErrRoomSensor       sysflag.bit4
#define             CoolDelayEnd       sysflag.bit5
#define             CoolLedFlash       sysflag.bit6
#define             McuPowerOn          sysflag.bit7
//*****************************************************************************
typedef             struct             BYTE_BIT
{
uchar             bit0:1;
uchar             bit1:1;
uchar             bit2:1;
uchar             bit3:1;
uchar             bit4:1;
uchar             bit5:1;
uchar             bit6:1;
uchar             bit7:1;
}BYTEBIT;
//-----------------------main.c------------------------------------------------------
BYTEBIT             sysflag;
//----------------------measure.c------------------------------------------------------
extern             BYTEBIT             sysflag;
看明白了怎么用吗?