# include & lt; Iostream> 
# include & lt; Event2/event. H> 
# include & lt; Event2/thread. H> 
# include & lt; Csignal> 


Void log_callback (int security, const char * MSG) 
{
STD: : cout & lt; <"The log: security=" & lt; Abort (); 
} 


Void event_callback (evutil_socket_t s, short event, void * arg) 
{
STD: : cout & lt; <"SIGINT triggered, exit loop" & lt; Struct event_base * eb=(struct event_base *) (arg); 
If (eb!=NULL) 
{
Event_base_loopexit (eb, NULL); 
} 
} 

Int _tmain (int arg c, _TCHAR * argv []) 
{
Event_set_log_callback (log_callback); 
Event_set_fatal_callback (fatal_callback); 
//event_enable_debug_logging (EVENT_DBG_ALL); 
Event_enable_debug_mode (); 
Evthread_use_windows_threads (); 

Struct event_config * ec=event_config_new (); 
Event_config_set_flag (ec, EVENT_BASE_FLAG_STARTUP_IOCP); 
Event_config_require_features (ec, EV_FEATURE_ET); 

Struct event_base * eb=event_base_new_with_config (ec); 
If (eb!=NULL) 
{
Struct event * sigint=evsignal_new (eb, sigint, event_callback, eb); 

Event_base_dispatch (eb); 

Event_base_free (eb); 
} 
Event_config_free (ec); 

return 0; 

After this code in the link above libevent2 version, execute event_base_new_with_config (ec) always returns NULL, log_callback print out no event mechanism available, libevent enable iocp do ah, excuse me expert what went wrong this code, thanks a lot