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CLAD2017 - Fundamentals - Why do you have to be so negative

Active Participant

What is Numeric Value Out following execution of the VI?

 

Index Array Negative.png

 

a) -1

b) 0

c) 9

d) NaN

Combined.png

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Member

Here the answer is C,

what ever the negative index value we are giving it is going to take the"Index 0" nearest to any negative index.

Knight of NI

C

The negative index will just return the default for the data type (0 for numerics).  And it will just increment from there, so the second index will actually be index 0, giving 9.


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Member

C

Member

C

Active Participant

C

Member

C

Member

C, what they said above. 

Active Participant

Answer: C.  Nice one all.

 

Nice explanation from crossrulz.

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Member

C

Member

Can someone help?  This actually looks like the Numeric Value Out is connected to the second row which would make (by default) Index 0, therefore 9.  When I connect the Numeric Value Out to the first row (index -1), I get 0 every time, not 9.  Please help.

Active Participant

Hi CristinaM

It's all about the index.  If you specify an index that is outside of those that are valid for the input array (valid range for the input array in the question is 0 to 5 inclusive).  I chose an index of -1 in the question but you would have got 0 returned by Index Array for every index outside of 0 to 5.  You get 0 because that is the default value for a numeric in LabVIEW.  If LabVIEW can't work out what the value needs to be or you have not specified what the value should be, LabVIEW will use the default value for the data type.

 

Here are some early The Daily CLAD posts that look at default values (oh the nostalgia)!!

 

https://forums.ni.com/t5/The-Daily-CLAD/For-loop-iteration-control-6/ba-p/3473603

https://forums.ni.com/t5/The-Daily-CLAD/For-loop-iteration-control-4/ba-p/3473385

https://forums.ni.com/t5/The-Daily-CLAD/Case-Structure-output-tunnels/ba-p/3474191

 

Steve

Combined.png