In Linux header file epoll.h, I found the following code:
enum EPOLL_EVENTS
{
EPOLLIN = 0x001,
#define EPOLLIN EPOLLIN
...
}
What does it mean by #define EPOLLIN EPOLLIN?
#define EPOLLIN EPOLLIN
This defines the preprocessor macro EPOLLIN to be EPOLLIN.
It is probably defined for the purposes of later #ifdef EPOLLIN checks.