# Converts a string to title case, normalizing any mixed or upper case text first.
#
# @param input_string [String] The string to be converted.
# @return [String] The title-cased string.
# @raise [TypeError] If the input is not a String.
def to_title_case(input_string)
# Guard clause: validate input type
unless input_string.is_a?(String)
raise TypeError, "Input must be a valid String."
end
# 1. Downcase the string to normalize any all-caps or mixed-case text
# 2. Split the string into an array of words based on whitespace
# 3. Capitalize each word individually
# 4. Join the words back together with a single space
input_string.downcase.split.map(&:capitalize).join(' ')
end
# --- Example Usage ---
if __FILE__ == $PROGRAM_NAME
begin
puts to_title_case("string programming functions")
# Output: String Programming Functions
puts to_title_case("STRING PROGRAMMING FUNCTIONS")
# Output: String Programming Functions
rescue StandardError => e
warn "Error: #{e.message}"
exit(1)
end
end
# run:
#
# String Programming Functions
# String Programming Functions
#
