# Help with converting array to Static Array
**URL:** https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861
**Category:** New to Julia
**Tags:** convert, staticarrays, constructors
**Created:** [May 5, 2019, 5:24am UTC](https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861 "2019-05-05T05:24:34Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@StevenSiew](https://discourse.julialang.org/u/StevenSiew)
#### Post date: [May 5, 2019, 5:24am UTC](https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861/1 "2019-05-05T05:24:34Z")
I wish to speed up my datastructure by converting array type to Static Array but I encounter an error. What did I do wrong?
```julia
using StaticArrays
datetype = Array{Int64,1}
datestatictype = SVector{3,Int64}
function printdate(x::datetype)
println("year ",x[1]," month ",x[2]," day ",x[3])
end
function printdatestatic(x::datestatictype)
println("year ",x[1]," month ",x[2]," day ",x[3])
end
a = Int64[2019,5,6]
printdate(a)
b = SVector{3,Int64}[2019,5,6]
printdatestatic(b)
```
with output
```julia
_ _ _(_)_ | Documentation: https://docs.julialang.org
(_) | (_) (_) |
_ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help.
| | | | | | |/ _` | |
| | |_| | | | (_| | | Version 1.1.0 (2019-01-21)
_/ |\ __'_|_|_|\__'_| | Official https://julialang.org/ release
|__/ |
year 2019 month 5 day 6
ERROR: LoadError: MethodError: Cannot `convert` an object of type Int64 to an object of type SArray{Tuple{3},Int64,1,3}
Closest candidates are:
convert(::Type{SA<:StaticArray}, ::SA<:StaticArray) where SA<:StaticArray at /Users/ssiew/.julia/packages/StaticArrays/VyRz3/src/convert.jl:11
convert(::Type{SA<:StaticArray}, ::StaticArray) where SA<:StaticArray at /Users/ssiew/.julia/packages/StaticArrays/VyRz3/src/convert.jl:10
convert(::Type{SA<:StaticArray}, ::AbstractArray) where SA<:StaticArray at /Users/ssiew/.julia/packages/StaticArrays/VyRz3/src/convert.jl:22
...
Stacktrace:
[1] setindex!(::Array{SArray{Tuple{3},Int64,1,3},1}, ::Int64, ::Int64) at ./array.jl:767
[2] getindex(::Type{SArray{Tuple{3},Int64,1,3}}, ::Int64, ::Int64, ::Int64) at ./array.jl:353
[3] top-level scope at none:0
in expression starting at /Users/ssiew/juliascript/StaticArrayTest.jl:17
```
---
### Author:  [@tomaklutfu](https://discourse.julialang.org/u/tomaklutfu)
#### Post date: [May 5, 2019, 6:03am UTC](https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861/2 "2019-05-05T06:03:02Z")
You missed the parenthesis `b = SVector{3,Int64}([2019,5,6])`. Without that, it tries to construct an array of Svectors so the error.
---
### Author:  [@Elrod](https://discourse.julialang.org/u/Elrod)
#### Post date: [May 5, 2019, 6:33am UTC](https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861/3 "2019-05-05T06:33:50Z")
Note that you can also do
```julia
julia> b = @SVector [2019,5,6]
3-element SArray{Tuple{3},Int64,1,3} with indices SOneTo(3):
2019
5
6
julia> @macroexpand @SVector [2019,5,6]
:((SArray{Tuple{3},T,1,3} where T)((2019, 5, 6)))
```
This macro avoids creating any temporaries and is type stable. Therefore it should be fast on top of convenient.
---
### Author:  [@DNF](https://discourse.julialang.org/u/DNF)
#### Post date: [May 5, 2019, 7:33am UTC](https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861/4 "2019-05-05T07:33:45Z")
> [@tomaklutfu](#):
>
> ```julia
> b = SVector{3,Int64}([2019,5,6])
>
> ```
Don’t use `[]` here. Then you are making a vector and then converting it. Write
```julia
SVector{3}(2019, 5, 6)
```
or use the macro.
Edit: Actually, simply `SVector(2019, 5, 6)` will do.
---
### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [May 5, 2019, 8:25am UTC](https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861/5 "2019-05-05T08:25:17Z")
> [@DNF](#):
>
> Don’t use `[]` here. Then you are making a vector and then converting it.
You are of course right given the context, but all of the constructors
```julia
SVector{N,T}(vec)
SVector{T}(args...)
SVector(args...)
@SVector [args...]
```
are useful depending on the format of the input arguments, and whether the type is known or is meant to be figured out using promotion, and whether `N` is meant to be enforced/checked.
---
### Author:  [@DNF](https://discourse.julialang.org/u/DNF)
#### Post date: [May 5, 2019, 9:07am UTC](https://discourse.julialang.org/t/help-with-converting-array-to-static-array/23861/6 "2019-05-05T09:07:57Z")
Agreed, but since the poster was uncertain how to create `SVector`s in general, I considered it useful to mention the most obvious constructor.