# About three dot in julia vector

**URL:** <https://discourse.julialang.org/t/about-three-dot-in-julia-vector/91216>\
**Category:** General Usage\
**Tags:** vector\
**Created:** [December 4, 2022, 2:15pm UTC](https://discourse.julialang.org/t/about-three-dot-in-julia-vector/91216 "2022-12-04T14:15:52Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Xuekui\_wang](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xuekui_wang/32/30746_2.png) [@Xuekui\_wang](https://discourse.julialang.org/u/Xuekui_wang)\
**Post date:** [December 4, 2022, 2:15pm UTC](https://discourse.julialang.org/t/about-three-dot-in-julia-vector/91216/1 "2022-12-04T14:15:52Z")

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I am a newer to julia, and cannot understand the use of three dot although have read some documents.  
For example as follows: A is two elements vector of (x,y); B is six elements vector of (1,2,3,4,5,6); C is four elements vector of (1,2,3, y) and D is four elements vector of (x,4,5,6).  
How do I understand `...`here?  
Thank you very much for your help.

```julia
x, y = [1,2,3], [4,5,6]
A = [x, y]
B = [x..., y...]
C = [x..., y]
D = [x, y...]

```

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**Author:** ![nilshg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nilshg/32/2283_2.png) [@nilshg](https://discourse.julialang.org/u/nilshg)\
**Post date:** [December 4, 2022, 2:46pm UTC](https://discourse.julialang.org/t/about-three-dot-in-julia-vector/91216/2 "2022-12-04T14:46:47Z")

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Could you explain what exactly you have trouble with? I’m assuming you have read

[Frequently Asked Questions · The Julia Language](https://docs.julialang.org/en/v1/manual/faq/#What-does-the-)…-operator-do?

which explains what splatting is, and it seems (at least to me!) that you’ve got a good set of examples already:

```julia
julia> A = [x, y]
2-element Vector{Vector{Int64}}:
 [1, 2, 3]
 [4, 5, 6]

julia> B = [x..., y...]
6-element Vector{Int64}:
 1
 2
 3
 4
 5
 6

```

when we splat an argument it should be read as if each element of the splatted collection is a separate function argument, i.e.:

```julia
julia> [x..., y...] == [x[1], x[2], x[3], y[1], y[2], y[3]]
true

```

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<div class="post-metadata">

**Author:** ![Xuekui\_wang](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/xuekui_wang/32/30746_2.png) [@Xuekui\_wang](https://discourse.julialang.org/u/Xuekui_wang)\
**Post date:** [December 4, 2022, 3:13pm UTC](https://discourse.julialang.org/t/about-three-dot-in-julia-vector/91216/3 "2022-12-04T15:13:14Z")

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> [@nilshg](#):
>
> I’m assuming you have read

Thank you, nilshg, I have known the meaning of splatting, it treat each element in the vector as a new, separate element. I was very curious about this example just now, and I couldn’t understand the instructions in the manual.

Thank you very much for your immediately reply.