# Two equivalent codes but one returning error
**URL:** https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668
**Category:** New to Julia
**Created:** [June 21, 2023, 5:40pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668 "2023-06-21T17:40:08Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@Zerosum](https://discourse.julialang.org/u/Zerosum)
#### Post date: [June 21, 2023, 5:40pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/1 "2023-06-21T17:40:08Z")
I was wondering if the two codes are different, because the second one returns an error message of “invalid index : nothing of type Nothing”
```julia
ind_one_y = findfirst(surplus[q,:,x,2,mq] .> 0.0)
Code 1 :
if isnothing(ind_one_y) == true
thr_one_y = 1e+8
else thr_one_y = grids.y[ind_one_y] - grids.mq[mq]
end
Code 2 :
thr_one_y = ifelse(isnothing(ind_one_y) == true, 1e+8, grids.y[ind_one_y] - grids.mq[mq])
```
I’m just completely lost.
---
### Author:  [@nsajko](https://discourse.julialang.org/u/nsajko)
#### Post date: [June 21, 2023, 5:43pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/2 "2023-06-21T17:43:34Z")
> [@Zerosum](#):
>
> `isno`
`ifelse` behaves like functions do, all its arguments are evaluated. This includes `grids.y[ind_one_y]`, which then errors.
---
### Author:  [@Zerosum](https://discourse.julialang.org/u/Zerosum)
#### Post date: [June 21, 2023, 5:44pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/3 "2023-06-21T17:44:25Z")
Thank you very much. I didn’t realize there is such subtle difference.
---
### Author:  [@nsajko](https://discourse.julialang.org/u/nsajko)
#### Post date: [June 21, 2023, 5:44pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/4 "2023-06-21T17:44:32Z")
BTW the `== true` in `boolean == true` is redundant.
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### Author:  [@Zerosum](https://discourse.julialang.org/u/Zerosum)
#### Post date: [June 21, 2023, 6:01pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/5 "2023-06-21T18:01:05Z")
Thank you for pointing that out. A silly mistake 🙂
---
### Author:  [@Henrique\_Becker](https://discourse.julialang.org/u/Henrique_Becker)
#### Post date: [June 21, 2023, 6:25pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/6 "2023-06-21T18:25:38Z")
Note that Julia has a `?:` ternary operator like C/C++/Java and many other languages, so you can do:
```julia
thr_one_y = isnothing(ind_one_y) ? 1e+8 : grids.y[ind_one_y] - grids.mq[mq]
```
If you want to do it in a single-line.
---
### Author:  [@Benny](https://discourse.julialang.org/u/Benny)
#### Post date: [June 21, 2023, 6:50pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/7 "2023-06-21T18:50:57Z")
Like the ternary `?:` operator, the `if-else` form can also be done in one line if each branch is 1 full line:
```julia
# OP's code
if isnothing(ind_one_y) == true thr_one_y = 1e+8 else thr_one_y = grids.y[ind_one_y] - grids.mq[mq] end
# equivalent to Henrique's edit
thr_one_y = if isnothing(ind_one_y) 1e+8 else grids.y[ind_one_y] - grids.mq[mq] end
```
The `?` is better at delimiting the line imo
---
### Author:  [@Zerosum](https://discourse.julialang.org/u/Zerosum)
#### Post date: [June 21, 2023, 7:40pm UTC](https://discourse.julialang.org/t/two-equivalent-codes-but-one-returning-error/100668/8 "2023-06-21T19:40:44Z")
Thank you very much for everyone.
Indeed, I was trying ifelse to make the three-lined code to one.
Everything looks beautiful!