Using Timer with event

Question

Hi To better understand the use of Timer and Events I have built a mini application that is supposed to write the time every preset interval using the Timer class. It works for me except that I get the writing doubled each time. I have tried hard to understand the reason but for no avail. Can anyone run the attached small app and let me know what have I done wrong or how to make it write the time one per line? Thanks in advnce

Zoran Horvat · Answer

You're adding new event handler every time with line: rate.Tick += new EventHandler(writeData); This means that you've subscribed to Tick event as many times as timer ticked. Results of this situation become difficult to track because writeData toggles start/stop indicator whenever entered - now it enters once the first time twice the second time switching the timer off but first entrance started timer again and so on. A bit untraceable kind of code. Also you should not call btnStartStop_Click(sender e); from writeData because sender and e from writeData do not apply to btnStartStop_Click although it compiles. To correct the issue do the following: 1. Subscribe to Tick event only at the same place where you instantiate the timer. Instantiating the object as you did is a bit troublesome (I personally never use it). Better off create timer in constructor and subscribe to Tick event there. 2. Create a new method which starts timer. Call it from btnStartStop_Click when applicable and call it from writeData.

Crish · Answer

i think this is the perfect answer for Using Timer with event

Sam · Answer

Thanks Zoran. A perfect answer that solved my problem.