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c#regexcamelcasing

Splitting CamelCase with regex

I have this code to split CamelCase by regular expression:

Regex.Replace(input, "(?<=[a-z])([A-Z])", " $1", RegexOptions.Compiled).Trim();

However, it doesn't split this correctly: ShowXYZColours

It produces Show XYZColours instead of Show XYZ Colours

How do I get the desired result?

Solution

  • Unicode-aware

    (?=\p{Lu}\p{Ll})|(?<=\p{Ll})(?=\p{Lu})

    Breakdown:

    (?=               # look-ahead: a position followed by...
  \p{Lu}\p{Ll}    #   an uppercase and a lowercase
)                 #
|                 # or
(?<=              # look-behind: a position after...
  \p{Ll}          #   an uppercase
)                 #
(?=               # look-ahead: a position followed by...
  \p{Lu}          #   a lowercase
)                 #

    Use with your regex split function.

    EDIT: Of course you can replace \p{Lu} with [A-Z] and \p{Ll} with [a-z] if that's what you need or your regex engine does not understand Unicode categories.