我不明白为什么编译器会给我这个代码错误 [英] I don't understand why compiler is giving me error with this code

问题描述

我有以下C代码，对我来说似乎很正确.但是，clang编译器(实际上是gcc或任何其他C编译器)也有不同的看法.

I have the following C code, which looks very correct to me. However, the clang compiler (infact gcc or any other C compiler too) thinks otherwise.

typedef struct
{
    struct timeval td_start;
    struct timeval td_end;
} Timer;

void startTimer( struct Timer* ptimer ) 
{
    gettimeofday( &(ptimer->td_start), NULL );
}

void stopTimer( struct Timer* ptimer ) 
{
    gettimeofday( &(ptimer->td_end), NULL );
}

编译器给出以下警告和提示.错误消息.知道这里有什么问题吗?

The compiler gives the following waring & error messages. Any idea what is wrong here?

./timing.h:14:25: warning: declaration of 'struct Timer' will not be visible
      outside of this function [-Wvisibility]
void startTimer( struct Timer* ptimer )
                        ^
./timing.h:16:27: error: incomplete definition of type 'struct Timer'
    gettimeofday( &(ptimer->td_start), NULL );
                    ~~~~~~^
./timing.h:14:25: note: forward declaration of 'struct Timer'
void startTimer( struct Timer* ptimer )
                        ^
./timing.h:19:24: warning: declaration of 'struct Timer' will not be visible
      outside of this function [-Wvisibility]
void stopTimer( struct Timer* ptimer )
                       ^
./timing.h:21:27: error: incomplete definition of type 'struct Timer'
    gettimeofday( &(ptimer->td_end), NULL );
                    ~~~~~~^
./timing.h:19:24: note: forward declaration of 'struct Timer'
void stopTimer( struct Timer* ptimer )

推荐答案

删除struct关键字(因为您已经typedef删除了该结构，所以不需要它):

Remove the struct keyword (it's not needed since you've already typedefed the struct):

void startTimer( Timer* ptimer ) 
{
  ...

void stopTimer( Timer* ptimer ) 
{
  ...

或者，删除typedef:

struct Timer
{
    struct timeval td_start;
    struct timeval td_end;
};

void startTimer( struct Timer* ptimer ) 
{
  ...

void stopTimer( struct Timer* ptimer ) 
{
  ...

有关更多信息，请参见为什么我们应该键入def在C中经常使用的结构吗?

For more information, see Why should we typedef a struct so often in C?

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