Event Structures Boolean Controls #2

[SercoSteveB]

The following VI is run.  Some time later the user performs a left mouse button click and release on the 'stop' control.  What is the value of Numeric Value Out following the left click and release on the 'stop' control?

 

a) -1

b) 0

c) 1

d) Undetermined (the VI does not stop)

[srinath@elsys.in]

Ans D

the VI will never stop. Here we are disabling stop button so event never execute.so VI never stop

[sumasbhat]

Ans D.

we are disabling stop button. so we can not stop VI.

[srinath@elsys.in]

your correct sumasbhat.....

[Gabe712]

D)

stop button is disabled, can't click on a disabled FP object.

<<Taking CLAD exam tomorrow thanks to all! These exercises have been tons of help!

Wish me luck!

[SercoSteveB]

Good luck Gabe712. 

When you get back, can you please post your thoughts on the exam, suggest additional topics for us to to cover and anything else that you think might be of use to CLAD takers?

Steve

[RustyStrings]

what everyone else said

[mini09]

I agree with Srinath, Gabe712  and Sumasbhat.

[SercoSteveB]

Answer: D  Nice one srinath, sumasbhat, Gabe, RS and gnshmrthy.  Yep, unlike the Mouse Down event (in yesterdays question) we cannot generate a Value Changed event on a disabled control.

[giulio91]

I would have answered B: since the default value of Numeric Value Out is 0, and isn't written that its value was changed, I assume the value when starting the vi is still 0.

"What is the value of Numeric Value Out following the left click and release on the 'stop' control?"

the click and release of the button does not trigger that event, so while is true that the vi does not stop, it's also true that Numer Value Out is 0 after the user interaction.

Steve, could you give any comment please?

Giulio

[RustyStrings]

you make a good point the indicator still has a value that is readable and would default to 0, and would still be zero even if you click on the control

but I think the main point demonstrated here is that a disabled control will not change value and not trigger the event, so the the code will not stop which is correctly stated in answer D

perhaps if the indicator was initialized with a random number first and hidden, then changed to a known value and shown in the stop even there would be no other way to think about it

[crossrulz]

sometimes you just have to go with the "best" answer.  Part of D is stating that the VI does not stop, making it the better answer.

And if you want to split hairs, you could claim that somebody put a random value into "Numeric Value Out" before the VI was ran or it has some random default value.  So the value would still be whatever value it was set to before the VI was ran.

[RustyStrings]

Crossrulz make a good point the value could have been changed

[SercoSteveB]

Hi giulio91 you are correct I didn't think about that one when writing the question.

I would say that as a general rule for CLAD type questions it is a good idea to go with the obvious, as crossrulz suggests, and try to avoid over thinking it, we'll leave that for CLD's and CLA's questions....and anybody else who wants too.  When creating questions I think about a concept and attempt to write a question around it.  The concept for this one was definitely that if you Disable and Greyed Out a Control via a property node can you subsequently fire a Value Change Event via the Front Panel.

I bin loads of 'The Daily CLAD' questions following a 'what if, what then' type conversation with myself.  There are always going to be 'what ifs' that don't occur to me and its great for people to point them out here and spread the love.

[giulio91]

Thanks to all of you, good points.

I have my clad exam in a week and this daily clad is very useful!!