# Removes all non-numeric characters from a string, returning a new string containing only digits.
#
# @param input_string [String] The source string containing alphanumeric and special characters.
# @return [String] A new string containing only numeric digits (0-9).
# @raise [TypeError] If the input is not a String.
def remove_non_numeric(input_string)
# Guard clause: validate input type
unless input_string.is_a?(String)
raise TypeError, "Input must be a valid String."
end
# Use gsub with \D (non-digit character class) to replace all non-numeric characters with an empty string.
# This is equivalent togsub(/[^0-9]/, '') but more concise and idiomatic.
input_string.gsub(/\D/, '')
end
# --- Example Usage ---
if __FILE__ == $PROGRAM_NAME
begin
text = "123XYZ +9982-programming 10000000000001language"
# Process the string
cleaned_text = remove_non_numeric(text)
# Output results
puts "Original: #{text}"
puts "Cleaned: #{cleaned_text}"
rescue StandardError => e
warn "Error: #{e.message}"
exit(1)
end
end
# run:
#
# Original: 123XYZ +9982-programming 10000000000001language
# Cleaned: 123998210000000000001
#
