timming a event by arduino

Projects General Guidance
6 
// declare your variables, etc.
// all time related events are of type "unsigned long"
eventPinState = 0;
void loop(){
if ( (eventPinState== 0) && (digitalRead(eventPin) ==1){ // event was not started, now it is running
eventPinState = 1;
eventStartTime = millis();
}
if ( (eventPinState== 1) && (digitalRead(eventPin) ==0){ // event was running, now it is stopped
eventPinState = 0;
eventEndTime = millis();
eventDuration = eventEndTime - eventStartTime;
Serial.print("event duration in mS = ");
Serial.println (eventDuration);
}
}// end loop