# How to use Regex() function?
**URL:** https://discourse.julialang.org/t/how-to-use-regex-function/48891
**Category:** General Usage
**Tags:** regex
**Created:** [October 23, 2020, 4:00pm UTC](https://discourse.julialang.org/t/how-to-use-regex-function/48891 "2020-10-23T16:00:39Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@JianghuiDu](https://discourse.julialang.org/u/JianghuiDu)
#### Post date: [October 23, 2020, 4:00pm UTC](https://discourse.julialang.org/t/how-to-use-regex-function/48891/1 "2020-10-23T16:00:39Z")
`r"(?<=NH3\)\[)\w+(?=\])"` is ok but `Regex("(?<=NH3\)\[)\w+(?=\])")` reports
```julia
ERROR: LoadError: syntax: invalid escape sequence
```
why?
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### Author:  [@JianghuiDu](https://discourse.julialang.org/u/JianghuiDu)
#### Post date: [October 23, 2020, 4:04pm UTC](https://discourse.julialang.org/t/how-to-use-regex-function/48891/3 "2020-10-23T16:04:00Z")
OK. just figured out… Need to use `\\` instead of `\` . The documentation should have mentioned that …
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### Author:  [@christopher-dG](https://discourse.julialang.org/u/christopher-dG)
#### Post date: [October 23, 2020, 4:04pm UTC](https://discourse.julialang.org/t/how-to-use-regex-function/48891/4 "2020-10-23T16:04:21Z")
The string macro form doesn’t recognize `\` as an escape character, it’s just another character in the regex (which has its own escape functionality according to regex). But in normal Julia strings, if you use `\` it needs to be part of an escape sequence such as `\n` (newline) or `\\` (literal backslash). If you want to use the `Regex` constructor, you can use `Regex(raw"my_string \ with weird escapes")`.
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### Author:  [@jling](https://discourse.julialang.org/u/jling)
#### Post date: [October 23, 2020, 4:07pm UTC](https://discourse.julialang.org/t/how-to-use-regex-function/48891/6 "2020-10-23T16:07:31Z")
[https://docs.julialang.org/en/v1/manual/metaprogramming/#man-macros](https://docs.julialang.org/en/v1/manual/metaprogramming/#man-macros)
it does by showing you you need `\\` if you’re constructing via `Regex()`
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### Author:  [@JianghuiDu](https://discourse.julialang.org/u/JianghuiDu)
#### Post date: [October 23, 2020, 6:25pm UTC](https://discourse.julialang.org/t/how-to-use-regex-function/48891/7 "2020-10-23T18:25:20Z")
Cool. Maybe it should also be in `?help` …
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### Author:  [@Tamas\_Papp](https://discourse.julialang.org/u/Tamas_Papp)
#### Post date: [October 24, 2020, 11:18am UTC](https://discourse.julialang.org/t/how-to-use-regex-function/48891/8 "2020-10-24T11:18:16Z")
> [@JianghuiDu](#):
>
> should also be in `?help` …
This is not what `?help` does (try it out).