CODEWITHSUNDEEP
stringkotlincross-platformline-breaksrawstring
fredoverflow
fredoverflow

Reputation: 263320

Are line breaks in raw strings platform-dependent?

Are line breaks in raw strings platform-dependent?

val a = "one\ntwo";

val b = """one
two"""

println(a == b)

In other words, is the println statement above guaranteed to print true or not?

Upvotes: 7

Views: 2790

Answers (3)

mkobit
mkobit

Reputation: 47299

It appears to be intentional in that it compiles down to the newline character only. This forum post and the response comment from Roman Elizarov clarifies this.

 """    
 -first line    
 -second line 
 """.trimIndent() ```

compiles to

"-first line\n-secondline"

instead of

"-first line\r\n-second line"

Is this by design? Is there any official documentation about line separators in triple-quoted strings?

And the response:

Yes. It is so by design. There is a key requirement that behavior of the code should not depend on the platform it was compiled on. ...

The follow up action from the thread is KT-56021, an issue to document this case:

KT-56021: Docs: Mention that multiline strings always use NL separators regardless of the platform.

Upvotes: 0

Les
Les

Reputation: 10605

I would not consider it guarantee that a and b are equal. The Spec has this to say about raw string literals:

Kotlin has two types of string literals: escaped strings that may have escaped characters in them and raw strings that can contain newlines and arbitrary text.

  1. The spec doesn't say it's the same
  2. The spec makes a differentiation between "newline" and "arbitrary text"
  3. And in the link by @zsmb13 to a Kotlin discussion, a Kotlin engineer says the compiler does not preserve the newlines in raw strings (??).

So, if I were writing code to work across platforms, I would be explicit (at least until they are).

Upvotes: 0

zsmb13
zsmb13

Reputation: 89628

Unfortunately, I couldn't find any sources specifically stating this. It feels like something that should be in the docs.

There is, however, the intention action in IntelliJ that converts a raw string to an ordinary string. I think it should be safe to assume that this action should not change the meaning of your code (or if it does, that should be filed as a bug). If you try this on a raw string with a newline in it, you can see that it replaces the newline with a \n character.

You can see the source of the action here, and a test for it that expects it to convert the newline to \n here (before) and here (after).

Edit: here's a comment on an issue about raw strings that (as far as I understand) states that a raw string has \n line endings in it.

Upvotes: 1

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