[Absolute Beginner] Is this txt-splitter Rustlike?


Ok, so yesterday I wrote a very small program in Rust that splits up Files for me based on the Beginning of a Line.
(I come from a Dynamics NAV Background and I used this to split up an Export of a Complete Database).

But I am sure I made some mistakes and would like to know what the Rust Community thinks about this:

It took me quite a while to get it to work. I had some C/C++ lessons in School, but I’ve been coding C#, Java and (for the majority of my time) C/AL, so I lost some knowledge about the very low-level-stuff…

Some weird things I did, because it wouldn’t compile otherways:

  • I have to create a tmp.txt file, because otherwise by the time new_f gets used, it could not be initiated.
  • I have no idea when I have to use “”.to_string() or the &… I probabibly have to go through the Tutorial again for this one.
  • Instead of handling the line with invalid utf-8 formatting, I just simply do a unwrap_or("") and replace it with an empty line. This is my biggest concern…

I would be very glad if you guys could just give me some insight on where I should improve and change my code, for it to be cleaner and simpler.

Thanks already!


Hi, and welcome to Rust! You’re definitely not alone with some points that take getting used to.

A few comments:

  • new_name does not need to be scoped to the function.
  • Instead of creating a dummy file, you can use an Option for new_f.
  • Some to_strings are not necessary. For example, instead of a[x..y] == "literal".to_string(), use &a[x..y] == "literal". In general, mismatches between owned (String) and borrowed (&str) types should be resolved by borrowing the owned value (if possible).
  • to_string() is slower than to_owned() or into(), but probably not for much longer.
  • Instead of to_string() I prefer clone() if it’s already a String.
  • For more complex path operations, see std::path.
  • It’s good style to at least add .unwrap() for Result values where the compiler emits warnings. That way, you don’t ignore failures at runtime.

I put a version with these changes here: https://gist.github.com/birkenfeld/fb4ec61ec70f781b93f1


Sorry I didn’t reply sooner…

Thank you for your help!

The part about strings is actually pretty neat. I will try to remember to use the owned value if I have the chance to!

I already checked out your Version and it looks a lot cleaner. I’ll go ahead and make mine a bit more sorted out and dynamic as well. :slightly_smiling:

Thanks again!