Code Snippet: Changing Character Case

Within these castle walls be forged Mavens of Computer Science ...

— Merlin, The Coder

Print characters in uppercase or lowercase

Swift

let string = "For the world is hollow, and I have touched the sky!"
print(string.uppercased())
print(string.lowercased())

Python

string = "For the world is hollow, and I have touched the sky!"
print(string.upper())
print(string.lower())

Common Lisp

(let ((string "Hello, world!"))
  (write-line (string-upcase string))
  (write-line (string-downcase string)))