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Compiler Error C3711

'method': an non-managed event source method must return void or an integral type

You defined a method in the event source that did not return void or an integral type. To fix this error, make the event and event handler have a return type of void or an integral type such as int or long.

The following sample generates C3711:

// C3711.cpp
#include <atlbase.h>
#include <atlcom.h>
#include <atlctl.h>

class CEventSrc {
   __event float event1();   // C3711
   // try the following line instead
   // __event int event1();
   // also change the handler, below

class CEventRec {
   float handler1() {         // change float to int
      return 0.0;             // change 0.0 to 0
   void HookEvents(CEventSrc* pSrc) {
      __hook(CEventSrc::event1, pSrc, CEventRec::handler1);
   void UnhookEvents(CEventSrc* pSrc) {
      __unhook(CEventSrc::event1, pSrc, CEventRec::handler1);

int main() {