Comparing with nothing

General Usage
1

How to compare with the value nothing? I came up with this small piece of lines but it is not working.

A = [1,2,3]
if indexin(USER_INPUT,A) !==  nothing
       do_someething()
       end

Thank you

2 
julia> isnothing(nothing)
true
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3

indexin returns an Array so !== nothing will always be true. What do you want to do?

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4

The USE_INPUT is an integer.

indexin(2,A) results in 2
but indexin(4,A) results in nothing.

So, I would like to compare with the result.

5

As Kristoffer said, those are (zero dimensional) arrays. You could e.g. try

julia> any(isnothing, indexin(1, [1,2,3]))
false

julia> any(isnothing, indexin(9, [1,2,3]))
true
2 Likes
6

Why not use if USER_INPUT in A instead?

2 Likes
7 
if any(isnothing, indexin(9, [1,2,3])) === false
       println("wahoo")
       end

It works well,
Thank you

8

I am new Julia user. can you provide an example?

9 
if 9 in [1,2,3]
    println("wahoo")
end

if 2 in [1,2,3]
    println("wohoo")
end
4 Likes
10

This also works. Thank you