clearerr
#define clearerr(p) (!__isthreaded ? __sclearerr(p) : (clearerr)(p))
#define clearerr(p) ((void)((p)->_flag &= ~(_IOERR | _IOEOF)))
#undef clearerr
clearerr(FILE *iop)
clearerr(FILE *stream)
#define clearerr(p) ((void) ((p)->_flag &= ~(_IOERR | _IOEOF)))