Question

单片机c语言外部变量问题

我定义了一个位域结构体和共用体的嵌套函数，因为多个程序中都要调用到这个函数，所以想在主函数中声明其为外部变量，这样就可以在被调函数中引用了，我声明方式与声明一般的变量方式一样，在.c文件中定以在.h文件中进行声明，但是怎么声明都不通过。。望大侠们多指教，共用结构体如下：
union unxs
{
struct stxs
{
unsigned char bit0: 1;
unsigned char bit1: 1;
unsigned char bit2: 1;
unsigned char bit3: 1;
unsigned char bit4: 1;
unsigned char bit5: 1;
unsigned char bit6: 1;
unsigned char bit7: 1;
} jg_byte;
unsigned char gy_byte;
} lcd_wz;
要是好的话，还会再加分，谢谢了先。

Answer 1

你在头文件中定义类型
typedef union unxs
{
struct stxs
{
unsigned char bit0: 1;
unsigned char bit1: 1;
unsigned char bit2: 1;
unsigned char bit3: 1;
unsigned char bit4: 1;
unsigned char bit5: 1;
unsigned char bit6: 1;
unsigned char bit7: 1;
} jg_byte;
unsigned char gy_byte;
} UNXS;

然后在C文件里定义变量
UNXS lcd_wz;

最在在要引用的地方或是头文件里声明一下
extern UNXS lcd_wz;就可以了。

Answer 2

#IFNDEF ABC_UNION
#DEFINE ABC_UNION
union unxs
{
struct stxs
{
unsigned char bit0: 1;
unsigned char bit1: 1;
unsigned char bit2: 1;
unsigned char bit3: 1;
unsigned char bit4: 1;
unsigned char bit5: 1;
unsigned char bit6: 1;
unsigned char bit7: 1;
} jg_byte;
unsigned char gy_byte;
} lcd_wz;

#ENDIF