这样引用联合体的成员为什么不行？

只看该作者 · 2015-2-7 11:19

typedef struct //¶¨Òå·¢ËÍÖ¡½á¹¹Ìå
{
uint8_t  FrameHead_1;
uint8_t  FrameHead_2;
uint8_t  FrameID;
uint8_t  FrameCount;
int16_t  AngleInt1;
int16_t  AngleInt2;
uint8_t  StatusWord;
int16_t  Rsv;
uint8_t  TxCheckSum;
} StructTxFrame;

typedef union          //¶¨Òå·¢ËÍÖ¡¹²ÓÃÌå
{
StructTxFrame TxFrame;
uint8_t TxBuffer[16];
} UnionTxFrame;
UnionTxFrame UniTxFrame = { 0} ;

UniTxFrame.TxFrame.AngleInt1 = 1;

编译提示最后一行错误： error:  #77-D: this declaration has no storage class or type specifier
                              error:  #147: declaration is incompatible with "UnionTxFrame UniTxFrame" (decl                                           ared at line 31)

只看该作者 · 2015-2-7 13:11

没有不行，赋值本来就不能在函数体外面

typedef struct                      //¶¨Òå·¢ËÍÖ¡½á¹¹Ìå
{
uint8_t  FrameHead_1;
      uint8_t  FrameHead_2;
      uint8_t  FrameID;
      uint8_t  FrameCount;
      int16_t  AngleInt1;
      int16_t  AngleInt2;
      uint8_t  StatusWord;
      int16_t  Rsv;
      uint8_t  TxCheckSum;
} StructTxFrame;

typedef union             //¶¨Òå·¢ËÍÖ¡¹²ÓÃÌå
{
StructTxFrame TxFrame;
      uint8_t TxBuffer[16];
} UnionTxFrame;
UnionTxFrame UniTxFrame = { 0} ;

void test（void）
{
      UniTxFrame.TxFrame.AngleInt1 = 1;
}