Control array with 1 DoubleClick event handler, how to determine which control initiated event?

Ramon Liverance

I have a screen with an array of labels (coded as: label[] aLabel = new label[30];
I would like to write a single DoubleClick event that handles all Double Click events for the array but action taken would be unique for the aLabel[] clicked. Therefore I have to determine which aLabel was DoubleClicked - there in lies the problem. There seems to be no way of determining the index value of the aLabel initiating the event. the sender data (in the event handler) can be viewed when in debug mode in VS2008 but there is no way of access this data withou knowning which indexed aLabel was clicked.
Any ideas??? this is driving me crazy and I'd hate to have to create 31 event handles, one for each indexed aLabel.

6 Replies

Know the answer? Post it — somebody with the same question will find it here.

Sam Hobbs16y ago
Yes it helps to understand that "sender" can be cast to something else; whatever the object actually is.
Ramon Liverance16y ago
Thanks VERY much, this makes it a lot easier! I am coming over from the older VB side and just haven't had to write anything with control arrays using MS provided events, I figured there had to be a way to do this. I was heading towards something like using the TAB field but then of course when I tried it I had the 'doh' moment that I didn't know the index. Kind of an internal circular reasoning that I kept on beating my head over. Your solution makes perfect sense, just couldn't seem to figure out how to ask the question in a search engine and my mental block on 'sender' type just did me in.
Thanks again.
Sam Hobbs16y ago
In the event handler, sender is the control. So do something such as:

Label l = sender as Label;

Then l.Tag is the Tag.
Ramon Liverance16y ago
Sam,
How would you read the tag property without first knowing the index? I'm somewhat new to this piece of C# so any additional info to ease the pain would be great. The problem I had with reading ANYTHING from within the event handler (that builtin DoubleClick handler) is that I first needed to know the fully qualified control name, including the index#. Once determined then of course I could read the tag with a simple 'aLabel[index].tag' but without the index I was toast. I really couldn't seem to find any alternative to the compare with the sender...
Sam Hobbs16y ago
There are many ways you could search the array without having to write the code using if statements or a big switch.

Even better, just set the label's Tag property to something, such as the array index. The Tag property can be any object; it could be an instance of a class with much more data.
Ramon Liverance16y ago
Solution: to determine control that initiates event (and hence the array element) it's as simple as adding this snippet of code in the event handler:
if (sender == aLabel[0]) {int arrayIndex = 0;]
if (sender == aLabel[1]) {int arrayIndex = 1;}
Of course you could use a SWITCH/CASE statement, a FOR Loop etc. as well. As luck would have it I spent the better part of a day looking for the answer and testing various ideas only to stumble on the answer as soon as I put the question up on the Forum here. Sorry! :-)