# Seeking explanation of Julia code using map! , BitVector and | operator

**URL:** https://discourse.julialang.org/t/seeking-explanation-of-julia-code-using-map-bitvector-and-operator/115980
**Category:** New to Julia
**Tags:** question
**Created:** [June 21, 2024, 3:59pm UTC](https://discourse.julialang.org/t/seeking-explanation-of-julia-code-using-map-bitvector-and-operator/115980 "2024-06-21T15:59:37Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![oOosys](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ooosys/32/209566_2.png) [@oOosys](https://discourse.julialang.org/u/oOosys)
#### Post date: [June 21, 2024, 3:59pm UTC](https://discourse.julialang.org/t/seeking-explanation-of-julia-code-using-map-bitvector-and-operator/115980/1 "2024-06-21T15:59:37Z")

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```julia
~ $ julia
               _
   _ _ _(_)_ | Documentation: https://docs.julialang.org
  (_) | (_) (_) |
   _ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` | |
  | | |_| | | | (_| | | Version 1.10.4 (2024-06-04)
 _/ |\ __'_|_|_|\__'_| | Official https://julialang.org/ release
|__/ |

julia> a = BitVector([0,1])
2-element BitVector:
 0
 1

julia> b = BitVector([1,0])
2-element BitVector:
 1
 0

julia> map!(|,a,b)
2-element BitVector:
 1
 0

```

---

<div class="post-metadata">

### Author: ![Jeff\_Emanuel](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeff_emanuel/32/15440_2.png) [@Jeff\_Emanuel](https://discourse.julialang.org/u/Jeff_Emanuel)
#### Post date: [June 21, 2024, 4:54pm UTC](https://discourse.julialang.org/t/seeking-explanation-of-julia-code-using-map-bitvector-and-operator/115980/2 "2024-06-21T16:54:22Z")

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```julia
help?> map!

  map!(function, destination, collection...)

```

Note the destination parameter.