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How can I remove all trailing backslashes from a string in Scala?

I want to remove all trailing backslashes ('') from a string.

''

For example:

"ab" -> "ab"
"ab\\" -> "ab"
"\\ab\" -> "\\ab"
"\" -> ""


I am able to do this using below code but unable to handle the scenario where the String has only slash(es). Please let me know if this can be achieved through a different regex.

val str = """\\q\"""
val regex = """^(.*[^\])(\+)$""".r
str match
case regex(rest, slashes) => str.stripSuffix(slashes)
case _ => str



str.replaceFirst("\\+$", "");

str.replaceFirst("""\+$""", "");

5 Answers
5

Converting my comment as an answer. This should work for removing all trailing backslashes:

str = str.replaceFirst("\\+$", "");


\\+ matches 1+ backslashes (single backslash is entered as \\ in Java/Scala).

\\+

\\

While not a regex, I suggest a simpler solution : str.reverse.dropWhile(_ == '\').reverse

str.reverse.dropWhile(_ == '\').reverse

Not using a regex, but you could use String.lastIndexWhere(p: (Char) ⇒ Boolean) to get the position of the last character which is not a '' in order to substring until this character:

String.lastIndexWhere(p: (Char) ⇒ Boolean)

''

str.substring(0, str.lastIndexWhere(_ != '\') + 1)


If, for some reason, you're committed to a regex solution, it can be done.

val regex = """[^\]?(\*)$""".r.unanchored
str match
case regex(slashes) => str.stripSuffix(slashes)



"""\+$""".r.unachored

+

*

You can do the same with slice function

slice

str.slice(0,str.lastIndexWhere(_ != '\')+1)


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