EventSet an integer handle to a PAPI event set as created by PAPI_create_eventset
overflow_vector a vector with bits set for each counter that overflowed. This vector is passed by the system to the overflow handler routine.
*array an array of indexes for events in EventSet. No more than *number indexes will be stored into the array.
*number On input the variable determines the size of the array. On output the variable contains the number of indexes in the array.

PAPI_EINVAL One or more of the arguments is invalid. This could occur if the overflow_vector is empty (zero), if the array or number pointers are NULL, if the value of number is less than one, or if the EventSet is empty.
PAPI_ENOEVST The EventSet specified does not exist.

void handler(int EventSet, void *address, long_long overflow_vector, void *context){
int Events[4], number, i;
int total = 0, retval;
printf("Overflow #%d\n  Handler(%d) Overflow at %p! vector=%#llx\n",
total, EventSet, address, overflow_vector);
total++;
number = 4;
retval = PAPI_get_overflow_event_index(EventSet,
overflow_vector, Events, &number);
if(retval == PAPI_OK)
for(i=0; i<number; i++) printf("Event index[%d] = %d", i, Events[i]);}