# What function do we use in Julia in place of cin\>\> in C++? how to input number in Julia from keyboard? Can I create vector from keyboard in Julia?

**URL:** <https://discourse.julialang.org/t/what-function-do-we-use-in-julia-in-place-of-cin-in-c-how-to-input-number-in-julia-from-keyboard-can-i-create-vector-from-keyboard-in-julia/26285>\
**Category:** New to Julia\
**Created:** [July 12, 2019, 11:24am UTC](https://discourse.julialang.org/t/what-function-do-we-use-in-julia-in-place-of-cin-in-c-how-to-input-number-in-julia-from-keyboard-can-i-create-vector-from-keyboard-in-julia/26285 "2019-07-12T11:24:47Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Dito](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dito/32/10039_2.png) [@Dito](https://discourse.julialang.org/u/Dito)\
**Post date:** [July 12, 2019, 11:24am UTC](https://discourse.julialang.org/t/what-function-do-we-use-in-julia-in-place-of-cin-in-c-how-to-input-number-in-julia-from-keyboard-can-i-create-vector-from-keyboard-in-julia/26285/1 "2019-07-12T11:24:48Z")

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function F(a=parse(Float64,readline()))  
@show a  
end

F()

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**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [July 12, 2019, 11:31am UTC](https://discourse.julialang.org/t/what-function-do-we-use-in-julia-in-place-of-cin-in-c-how-to-input-number-in-julia-from-keyboard-can-i-create-vector-from-keyboard-in-julia/26285/2 "2019-07-12T11:31:24Z")

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You already found `readline`, which answers your first question.

It returns a string, which you have to process.

Look at `?parse` and `?tryparse` for parsing numbers.

To parse a vector, the best strategy is to split it to components (you could use Julia’s code parser, but that allows arbitrary code, so it is not recommended). Use `split` or [regular expressions](https://docs.julialang.org/en/v1/manual/strings/#Regular-Expressions-1).

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**Author:** ![Per](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/per/32/10387_2.png) [@Per](https://discourse.julialang.org/u/Per)\
**Post date:** [July 12, 2019, 12:11pm UTC](https://discourse.julialang.org/t/what-function-do-we-use-in-julia-in-place-of-cin-in-c-how-to-input-number-in-julia-from-keyboard-can-i-create-vector-from-keyboard-in-julia/26285/3 "2019-07-12T12:11:53Z")

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> [@Tamas\_Papp](#):
>
> (you could use Julia’s code parser, but that allows arbitrary code, so it is not recommended

Why not? It’s not like it actually evaluates the code.

```julia
julia> function parsevector(T, str)
           expr = Meta.parse(str)
           if expr.head == :vect
             Vector{T}(expr.args)
           else
             error("could not parse")
           end
         end

julia> parsevector(Int, "[1, 2, 3]")
3-element Array{Int64,1}:
 1
 2
 3

```

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<div class="post-metadata">

**Author:** ![Tamas\_Papp](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/tamas_papp/32/25949_2.png) [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)\
**Post date:** [July 12, 2019, 1:04pm UTC](https://discourse.julialang.org/t/what-function-do-we-use-in-julia-in-place-of-cin-in-c-how-to-input-number-in-julia-from-keyboard-can-i-create-vector-from-keyboard-in-julia/26285/4 "2019-07-12T13:04:43Z")

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The way you did it is OK I think (because nothing else should be able to get through); I was thinking of converting with `eval`.