# How to replace backslash

**URL:** <https://discourse.julialang.org/t/how-to-replace-backslash/129816>\
**Category:** New to Julia\
**Tags:** regex\
**Created:** [June 11, 2025, 5:19pm UTC](https://discourse.julialang.org/t/how-to-replace-backslash/129816 "2025-06-11T17:19:49Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![gvanuxem](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gvanuxem](https://discourse.julialang.org/u/gvanuxem)\
**Post date:** [June 11, 2025, 5:19pm UTC](https://discourse.julialang.org/t/how-to-replace-backslash/129816/1 "2025-06-11T17:19:49Z")

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Hello,

For example, this one does not work:

```julia
julia> replace("foo \spadbar{jjjd}","\\spad"=>"")
ERROR: ParseError:
# Error @ REPL[6]:1:21
ulia> replace("foo \spadbar{jjjd}","\\spad"=>"")
# └┘ ── invalid escape sequence
Stacktrace:
 [1] top-level scope
   @ none:1

```

The first string is extracted from a database and contains some TeX like strings.

Regards,

Greg

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<div class="post-metadata">

**Author:** ![mikmoore](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mikmoore/32/31109_2.png) [@mikmoore](https://discourse.julialang.org/u/mikmoore)\
**Post date:** [June 11, 2025, 5:41pm UTC](https://discourse.julialang.org/t/how-to-replace-backslash/129816/2 "2025-06-11T17:41:00Z")

</div>

> [@gvanuxem](#):
>
> `replace("foo \spadbar{jjjd}","\\spad"=>"")`

I’m not sure I understand the question. Your error is getting thrown because it’s trying to parse `\s` as a special character (which doesn’t exist) when it creates the original string (long before it ever tries to call `replace`). You did the correct thing in your `"\\spad"`, which is to escape the `\` as `\\`.

What you have works fine if I use

```julia-repl
julia> "foo \spadbar{jjjd}" # original string is invalid
ERROR: ParseError:
# Error @ REPL[162]:1:7
"foo \spadbar{jjjd}"
# └┘ ── invalid escape sequence

julia> "foo \\spadbar{jjjd}" # this might look like it has two backslashes
"foo \\spadbar{jjjd}"

julia> println("foo \\spadbar{jjjd}") # but printing reveals it only has one backslash
foo \spadbar{jjjd}

julia> replace("foo \\spadbar{jjjd}","\\spad"=>"") # with the backslash escape'd
"foo bar{jjjd}"

julia> replace(raw"foo \spadbar{jjjd}","\\spad"=>"") # use raw"" to take the string literally without escape characters
"foo bar{jjjd}"

```

But if you’re extracting the string from a database then this should never have been a problem since it’s being read from a file/data rather than input (unless you’re using `eval`, `Meta.parse`, or something else you should avoid). So I’m not certain this resolves your issue.

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<div class="post-metadata">

**Author:** ![gvanuxem](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gvanuxem](https://discourse.julialang.org/u/gvanuxem)\
**Post date:** [June 12, 2025, 10:01am UTC](https://discourse.julialang.org/t/how-to-replace-backslash/129816/3 "2025-06-12T10:01:51Z")

</div>

Oh, excellent! And hello of course,

raw"string" is exactly what I was looking for. I did not remember it, and in this context ‘replace’ and not “print” it, I hadn’t thought about this. Many thanks.

About the database it’s an internal base and I use libbuila to call Julia from C. The extracted information contains some TeX-like constructs that were badly handled. Right now, I still need to remove some double quotes characters but that helped a lot i.e. let me go ahead.

Thanks again,

\_\_  
Greg

PS: BTW, from my tests, replace(“foo \spadbar{jjjd}”,“\spad”=\>“”) does not work in my settings, the CAS interpreter/compiler I am working on uses ‘\_’ as escape character and apparently mixing the two is relatively not handy, at least for me.