cohen
String.replace and escaping weirdness
I have some code that finds all instances of the characters , %, and _, inserting a backslash in front of them to escape them in the resulting SQL string. I’m a little bit confused about the amount of \ characters I need to use to do this. I would think that String.replace(string, ~r/([\\%_])/, "\\\\1") would do it, since I put in "\\" for a single backslash, then "\\1" for the backslash-one syntax to get my first capture. However, this results in substituting the characters backslash and 1, e.g., a_b → a\1b (on IO.puts).
It seems like this because "\\\\1" is the intended syntax for substituting an actual, literal backslash and "\\\\\\1" does the trick, but to be honest I’'m confused about how the escaping is actually working in this case.
Does anyone have any insights?
Most Liked
NobbZ
In the replacement language \ has a special meaning. So if you want it literally, you need to escape it.
Your string \\\\1 is seen by the replacement language as \\1, which will result in the replace of \1 (as printed) or \\1 (as inspected).
To actually get a single backslash followed by the content of the capture, you need 3 backslashes followed by a one in the replacement language, which in a string literall have to be doubled, such that you end up with 6 of them.
When I do write replacments, I usually use ~S to avoid the duplication, then I can do ~S"\\\1".
Popular in Questions
Other popular topics
Latest on Elixir Forum
Sponsor Spotlight
We build reliable cloud platforms for business-critical systems.
Categories:
Sub Categories:
Forums
Popular Tags
- #ecto
- #liveview
- #troubleshooting
- #learning-elixir
- #deployment
- #library
- #erlang
- #testing
- #genserver
- #mix
- #absinthe
- #remote-other
- #otp
- #plug
- #how-to-question
- #macros
- #postgres
- #channels
- #elixirconf
- #exunit
- #discussion
- #code-sync
- #javascript
- #podcasts
- #onsite
- #dialyzer
- #docker
- #authentication
- #umbrella
- #full-time-contract
- #podcasts-by-brainlid
- #ecto-query
- #elixir-ls
- #phoenix_html
- #iex
- #blog-post
- #graphql
- #genstage
- #ai
- #websockets
- #supervisor
- #advent-of-code
- #elixirconf-us
- #distillery
- #processes
- #forms
- #api
- #metaprogramming
- #security
- #performance
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Catch errors, track performance, monitor hosts and more.
Error tracking for Elixir devs who love to ship. Start your free account.
Develop your skills with books, videos, and courses.
Producing high quality Elixir screencasts since 2017.
Enabling companies to succeed by building software people love.
The team behind Membrane, Popcorn, LiveDebugger. Available for hire.
Courses that'll move you from confusion to "Aha, now I get it!"