Example regular expressions for converting strings to CamelCase or snake_case

Ruby regular expression for CamelCase and snake_case.rb

original = 'ThisIsAStringInCamelCaseWithNumbersLike12And14'

# Convert a CamelCase string to snake_case
snake_case = original.gsub(/([\w^_](?=[A-Z]))|([a-z](?=\d+))/, '\1\2_').downcase

# Convert a snake_case string to CamelCase
camel_case = snake_case.gsub(/^\w|_\w/) { |match| match[-1,1].upcase }

puts snake_case # => "this_is_a_string_in_camel_case_with_numbers_like_12_and_14"
puts camel_case # => "ThisIsAStringInCamelCaseWithNumbersLike12And14"