[C++] String swap case kernel

[asfimport]

Changes lowercase characters to uppercase and uppercase characters to lowercase, like Python str.swapcase()

Reporter: Ian Cook / @ianmcook
Assignee: Christian Cordova / @Christian8491

Related issues:

• [C++] String algorithm library for StringArray/BinaryArray (is a child of)
• [C++] String title case kernel (relates to)
• [C++] String capitalize kernel (relates to)

PRs and other links:

• GitHub Pull Request #10855

_{Note: This issue was originally created as ARROW-12946. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
@edponce

[asfimport]

Antoine Pitrou / @pitrou:
Issue resolved by pull request 10855
#10855