# ERROR: UndefVarError: A not defined

**URL:** <https://discourse.julialang.org/t/error-undefvarerror-a-not-defined/37948>\
**Category:** New to Julia\
**Created:** [April 21, 2020, 6:52am UTC](https://discourse.julialang.org/t/error-undefvarerror-a-not-defined/37948 "2020-04-21T06:52:30Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![QUANG\_VU\_NGUY\_N\_PH\_M](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/quang_vu_nguy_n_ph_m/32/14299_2.png) [@QUANG\_VU\_NGUY\_N\_PH\_M](https://discourse.julialang.org/u/QUANG_VU_NGUY_N_PH_M)\
**Post date:** [April 21, 2020, 6:52am UTC](https://discourse.julialang.org/t/error-undefvarerror-a-not-defined/37948/1 "2020-04-21T06:52:30Z")

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g(x) = 2 + x  
A = 0

for i =1:2  
A += g(i)  
end

I got an error: ERROR: UndefVarError: A not defined.  
I thought that I defined A = 0 before the loop. How to fix this?  
Thank you in advanced!

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<div class="post-metadata">

**Author:** ![QUANG\_VU\_NGUY\_N\_PH\_M](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/quang_vu_nguy_n_ph_m/32/14299_2.png) [@QUANG\_VU\_NGUY\_N\_PH\_M](https://discourse.julialang.org/u/QUANG_VU_NGUY_N_PH_M)\
**Post date:** [April 21, 2020, 7:03am UTC](https://discourse.julialang.org/t/error-undefvarerror-a-not-defined/37948/2 "2020-04-21T07:03:21Z")

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I found out that I need to add global

```julia
g(x) = 2 + x
A = 0

for i =1:2 
           global A += g(i)
end

```

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**Author:** ![mauro3](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mauro3/32/292_2.png) [@mauro3](https://discourse.julialang.org/u/mauro3)\
**Post date:** [April 21, 2020, 7:04am UTC](https://discourse.julialang.org/t/error-undefvarerror-a-not-defined/37948/3 "2020-04-21T07:04:13Z")

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Or

```julia
g(x) = 2 + x
function f()
A = 0
for i =1:2 
  A += g(i)
end
return A
end

```

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<div class="post-metadata">

**Author:** ![QUANG\_VU\_NGUY\_N\_PH\_M](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/quang_vu_nguy_n_ph_m/32/14299_2.png) [@QUANG\_VU\_NGUY\_N\_PH\_M](https://discourse.julialang.org/u/QUANG_VU_NGUY_N_PH_M)\
**Post date:** [April 21, 2020, 7:16am UTC](https://discourse.julialang.org/t/error-undefvarerror-a-not-defined/37948/4 "2020-04-21T07:16:48Z")

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thank you. this occur when I upgrade Julia version. A bit confusing …

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<div class="post-metadata">

**Author:** ![mauro3](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mauro3/32/292_2.png) [@mauro3](https://discourse.julialang.org/u/mauro3)\
**Post date:** [April 21, 2020, 7:50am UTC](https://discourse.julialang.org/t/error-undefvarerror-a-not-defined/37948/5 "2020-04-21T07:50:54Z")

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From pre 1.0 (or 0.7), right? (Remember to use 0.7 to get deprecation warnings during upgrade)