# How to find index in String Array

**URL:** <https://discourse.julialang.org/t/how-to-find-index-in-string-array/5901>\
**Category:** General Usage\
**Created:** [September 15, 2017, 10:17am UTC](https://discourse.julialang.org/t/how-to-find-index-in-string-array/5901 "2017-09-15T10:17:57Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![programista](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/programista/32/5372_2.png) [@programista](https://discourse.julialang.org/u/programista)\
**Post date:** [September 15, 2017, 10:17am UTC](https://discourse.julialang.org/t/how-to-find-index-in-string-array/5901/1 "2017-09-15T10:17:57Z")

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How to find index in String Array

Version 0.5.0 (2016-09-19 18:14 UTC)  
Official [http://julialang.org/](http://julialang.org/) release  
x86\_64-w64-mingw32

julia\> userstemp  
5-element Array{String,1}:  
“aa”  
“ab”  
“ac”  
“ad”  
“zz”

julia\> indexin(userstemp,“aa”)  
ERROR: MethodError: no method matching indexin(::Array{String,1}, ::String)  
Closest candidates are:  
indexin(::AbstractArray{T,N}, ::AbstractArray{T,N}) at array.jl:1326

julia\> in(userstemp,“aa”)  
false

julia\> findin(userstemp,“aa”)  
0-element Array{Int64,1}

julia\> findin(userstemp,‘aa’)  
ERROR: syntax: invalid character literal

julia\> indexin(userstemp,‘aa’)  
ERROR: syntax: invalid character literal

Paul

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<div class="post-metadata">

**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [September 15, 2017, 10:32am UTC](https://discourse.julialang.org/t/how-to-find-index-in-string-array/5901/2 "2017-09-15T10:32:19Z")

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`find(x -> x=="aa", ["aa", "ab", "ac"])` or to just match the first `findfirst(x -> x=="aa", ["aa", "ab", "ac"])`.

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<div class="post-metadata">

**Author:** ![programista](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/programista/32/5372_2.png) [@programista](https://discourse.julialang.org/u/programista)\
**Post date:** [September 15, 2017, 10:55am UTC](https://discourse.julialang.org/t/how-to-find-index-in-string-array/5901/3 "2017-09-15T10:55:58Z")

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Thanks Fredig, but why dosen`t work findin([“aa”,“ab”,“ac”],“aa”) ?  
Paul  
W dniu 2017-09-15 o 12:37, Fredrik Ekre pisze:

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**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [September 15, 2017, 11:14am UTC](https://discourse.julialang.org/t/how-to-find-index-in-string-array/5901/4 "2017-09-15T11:14:09Z")

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`findin(["aa", "ab"], ["aa"])`